Illumination device

Abstract

To provide an illumination device that can suppress power consumption, and efficiently raise plants.SOLUTION: An illumination device according to an embodiment of the present invention emits light having a continuous spectrum within a wavelength range of at least 420 nm or more and 750 nm or less, wherein light has: a first maximum peak wavelength which becomes the maximum peak in a first wavelength range of 430 nm or more and 470 nm or less; a second maximum peak wavelength which becomes the maximum peak in a second wavelength range of 530 nm or more and 570 nm or less; and a third maximum peak wavelength which becomes the maximum peak in a third wavelength range of 640 nm or more and 680 nm or less, and the emission intensity of the third maximum peak wavelength is larger than the emission intensity of the first maximum peak wavelength.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a lighting device using an LED (Light Emitting Diode), and more particularly to a technique for emitting illumination light that is excellent for plant growth. [Background technology]

[0002] As a plant growing device using an artificial light source, a device that takes into consideration the wavelength and light distribution of the light source for plant growth has been proposed. For example, Patent Document 1 describes a plant growing buffer device that has a white LED containing a blue LED chip and a yellow phosphor, and a blue-green LED. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Utility Model Registration No. 3158290 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, plant cultivation using artificial light sources has attracted attention, and LEDs have become increasingly popular as artificial light sources. However, there is a problem in that the power consumption of plant cultivation devices such as those described in Patent Document 1 increases in order to grow plants quickly and large.

[0005] In view of the above circumstances, an object of the present invention is to provide a lighting device that can reduce power consumption and efficiently grow plants. [Means for solving the problem]

[0006] In order to achieve the above object, an illumination device according to one aspect of the present invention is an illumination device that emits light having a continuous spectrum at least in a wavelength range of 420 nm to 750 nm, the light has a first maximum peak wavelength that is a maximum peak in a first wavelength range of 430 nm or more and 470 nm or less, a second maximum peak wavelength that is a maximum peak in a second wavelength range of 530 nm or more and 570 nm or less, and a third maximum peak wavelength that is a maximum peak in a third wavelength range of 640 nm or more and 680 nm or less, The emission intensity of the third maximum peak wavelength is greater than the emission intensity of the first maximum peak wavelength.

[0007] In the spectrum of the light, the emission intensity of the third maximum peak wavelength may be greater than the emission intensity of the second maximum peak wavelength.

[0008] In the spectrum of the light, the emission intensity of a minimum peak wavelength that is the minimum peak in a fourth wavelength range of 560 nm to 600 nm may be 20% to 100% of the emission intensity of the second maximum peak wavelength.

[0009] In the spectrum of the light, the emission intensity of the minimum peak wavelength in the fourth wavelength range may be 20% or more and 60% or less of the emission intensity of the second maximum peak wavelength.

[0010] In the spectrum of the light, the emission intensity of the minimum peak wavelength in the fourth wavelength range may be 35% or more and 45% or less of the emission intensity of the second maximum peak wavelength.

[0011] In the spectrum of the light, the maximum emission intensity in a fifth wavelength range of 700 nm to 750 nm may be 30% to 70% of the emission intensity of the second maximum peak wavelength.

[0012] In the spectrum of the light, the maximum emission intensity in the fifth wavelength range may be 60% or more and 70% or less of the emission intensity of the second maximum peak wavelength.

[0013] the light is a mixture of light emitted from the first LED having a continuous spectrum in the wavelength range of 420 nm to 750 nm and light emitted from the second LED having a continuous spectrum in the wavelength range of 500 nm to 750 nm, the first LED has a third maximum peak wavelength that is a maximum peak in the first wavelength range and is different from the first maximum peak wavelength, a fourth maximum peak wavelength that is a maximum peak in a wavelength range of 500 nm or more and 540 nm or less, and a fifth maximum peak wavelength that is a maximum peak in the third wavelength range and is different from the second maximum peak wavelength; The second LED may have a sixth maximum peak wavelength that is a maximum peak in the second wavelength range. [Effects of the Invention]

[0014] As described above, according to the present invention, it is possible to provide a lighting device that can reduce power consumption and efficiently grow plants. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 2 is a front view of the lighting device according to the embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing an emission spectrum of a first LED according to an embodiment of the present invention. [Figure 3] FIG. 4 is a diagram showing an emission spectrum of a second LED according to an embodiment of the present invention. [Figure 4] FIG. 2 is a diagram showing an emission spectrum of the lighting device according to the embodiment of the present invention. [Figure 5] FIG. 10 is a diagram showing the growth of leaf lettuce under each light source. [Figure 6] FIG. 10 is a diagram showing the growth of lettuce heads under different light sources. [Figure 7] FIG. 1 shows the growth of sunny lettuce under each light source. [Figure 8] 1A and 1B are diagrams showing the morphology of lettuce under different light sources, where (A) shows the morphology of head lettuce and (B) shows the morphology of sunny lettuce. [Figure 9]FIG. 10 is a diagram showing an emission spectrum of a first comparative light source in a comparative example. [Figure 10] FIG. 10 is a diagram showing an emission spectrum of a second comparative light source in a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0017] <Embodiment> Fig. 1 is a diagram showing a front view of a lighting device 1 according to an embodiment of the present invention. Fig. 2 is a diagram showing an emission spectrum of a first LED 30 of the lighting device 1. Fig. 3 is a diagram showing an emission spectrum of a second LED 40 of the lighting device 1. Fig. 4 is a diagram showing an emission spectrum of the lighting device 1. The lighting device 1 of the present invention is used, for example, to be installed indoors in a plant factory to grow plants.

[0018] The lighting device 1 has the overall shape of a straight-tube fluorescent lamp, and emits light when inserted into a fluorescent lamp socket. The lighting device 1 has a case 10 and an LED substrate 20. In this embodiment, the lighting device 1 is described as a straight-tube type, but of course it is not limited to this and may be a circular fluorescent lamp or a bulb-type fluorescent lamp, or may have a structure in which a light source and a power supply are housed in a housing, rather than being limited to a lamp shape with a base.

[0019] The case 10 is a structure for housing the LED substrate 20. Its length is, for example, about 120 cm, which is the size of a typical fluorescent lamp. The case 10 is cylindrical and includes a light diffusion section 11, electrodes 12, and a power source (not shown).

[0020] The light diffusion section 11 has a cylindrical structure that covers the LED substrate 20 and also serves to protect the LED substrate 20. It is made of a transparent or translucent material, such as glass or a resin such as acrylic or polycarbonate, and diffuses light from the LED substrate 20.

[0021] The electrode 12 is a terminal for supplying power from an external source to the LED substrate 20. It is inserted into a fluorescent lamp socket, and commercial power such as 100V is supplied from the socket to the inside of the case 10 via the electrode 12. However, without being limited to this, a DC power source may be connected from a power supply device and supplied to the inside of the case 10.

[0022] The power supply device is arranged on the back surface of the LED substrate 20 (opposite the surface on which the first LED 30 and the second LED 40 are arranged) and rectifies an AC voltage of 100 V or the like supplied from the outside and converts it into a DC voltage suitable for supply to the LED substrate 20 (not shown).

[0023] The LED substrate 20 is provided with first LEDs 30 and second LEDs 40. The LED substrate 20 is a rectangular substrate, with a longitudinal length of approximately 120 cm, which is close to the length of the case 10 of the lighting device 1. The width is a few centimeters. The first LEDs 30 and second LEDs 40, each approximately 3 mm square, are arranged on the LED substrate 20 in a 3:1 ratio. That is, as shown in FIG. 1, three first LEDs 30 are arranged in series, with one second LED 40 arranged next to them. In this embodiment, the first LEDs 30 and second LEDs 40 are arranged 10 mm apart, but this is not limiting. For example, two first LEDs 30 may be arranged 10 mm apart, and one second LED 40 may be arranged 10 mm apart next to the two first LEDs (the first LEDs 30 and second LEDs 40 may be arranged in a 2:1 ratio, as shown in FIG. 1). Alternatively, one first LED 30 may be arranged, and one second LED 40 may be arranged adjacent to it at 10 mm intervals (the first LED 30 and the second LED 40 may be arranged in a 1:1 ratio as shown in FIG. 1). Alternatively, four first LEDs 30 may be arranged at 10 mm intervals, and one second LED 40 may be arranged adjacent to the four first LEDs at 10 mm intervals (the first LED 30 and the second LED 40 may be arranged in a 4:1 ratio as shown in FIG. 1). Alternatively, five first LEDs 30 may be arranged at 10 mm intervals, and one second LED 40 may be arranged adjacent to the five first LEDs at 10 mm intervals (the first LED 30 and the second LED 40 may be arranged in a 5:1 ratio as shown in FIG. 1). 1, the first LEDs 30 and the second LEDs 40 are arranged in a ratio of 3:1, but the ratio is not limited to this and may be in the range of 1:1 (first LEDs 30:second LEDs 40) to 5:1 (first LEDs 30:second LEDs 40). The LEDs are electrically connected and emit light using power generated by the power supply device.

[0024] 2, the first LED 30 has a continuous spectrum in the wavelength range of at least 420 nm to 750 nm, and includes a first light-emitting diode 30A and a first phosphor film 30B. In this embodiment, the first LED 30 emits white light with a correlated color temperature of 5000 K, but the correlated color temperature is not limited to this and may be 4000 K or 6000 K.

[0025] A DC voltage is applied to the first light-emitting diode 30A from the LED substrate 20. The first light-emitting diode 30A lights up and emits light in response to the applied DC voltage. The first light-emitting diode 30A emits light having a fourth maximum peak wavelength 31 in which the emission intensity reaches a maximum peak (maximum) in a wavelength range of 430 nm to 470 nm (wavelength range of blue light, first wavelength range). A blue-emitting diode is used as the first light-emitting diode 30A.

[0026] The first phosphor film 30B is formed so as to cover the first light-emitting diode 30A. After light from the first light-emitting diode 30A is absorbed by the first phosphor film 30B, the first light-emitting diode 30A emits light having a fifth maximum peak wavelength 32 in which the emission intensity reaches a maximum peak (becomes maximum) in the wavelength range of 500 nm to 540 nm (the wavelength range of green light), and light having a sixth maximum peak wavelength 33 in which the emission intensity reaches a maximum peak (becomes maximum) in the wavelength range of 640 nm to 680 nm (the wavelength range of red light, the third wavelength range).

[0027] That is, the first phosphor film 30B is excited by the light from the first light emitting diode 30A and emits light having a fifth maximum peak wavelength 32 and light having a sixth maximum peak wavelength 33.

[0028] The first LED 30 further emits light having a second minimum peak wavelength 34 that becomes the minimum peak (becomes the smallest) in the wavelength range of 560 nm or more and 600 nm or less (the wavelength range of yellow light, the fourth wavelength range).

[0029] The light emitted from the first light emitting diode 30A and the light emitted from the first phosphor film 30B are combined to emit light having a desired correlated color temperature (5000K in this embodiment).

[0030] In addition, in this embodiment, the first LED 30 is composed of a first light-emitting diode 30A and a first phosphor film 30B, but of course this is not limited to this, and light having a desired correlated color temperature may be emitted by multiple light-emitting diodes.

[0031] Here, the maximum peak wavelength is the wavelength at which the emission intensity is greatest in the spectral portion that is convex upward, and the minimum peak is the wavelength at which the emission intensity is lowest in the spectral portion that is concave downward.

[0032] The emission spectrum of the first LED 30 will be described in detail. As shown in Figure 2, the first LED 30 has a continuous spectrum in the wavelength range of 420 nm to 750 nm. The vertical axis of Figure 2 represents photosynthetic photon flex density (PPFD) [mol / m²·s], and the horizontal axis represents wavelength (nm). Here, luminous intensity refers to the degree of photosynthetic photon flux density. In other words, high luminous intensity indicates a large number of photons reaching a specific area in a certain period of time. Below, the relationship between the vertical and horizontal axes in the figures will be the same as in Figure 2.

[0033] The fourth maximum peak wavelength 31 is more specifically in the wavelength range of 440 nm to 460 nm, and its center wavelength (peak wavelength) is approximately 450 nm. The fifth maximum peak wavelength 32 is more specifically in the wavelength range of 510 nm to 530 nm, and its center wavelength (peak wavelength) is approximately 520 nm. The sixth maximum peak wavelength 33 is more specifically in the wavelength range of 650 nm to 670 nm, and its center wavelength (peak wavelength) is approximately 660 nm. The second minimum peak wavelength 34 is more specifically in the wavelength range of 570 nm to 590 nm, and its center wavelength (peak wavelength) is approximately 580 nm.

[0034] The luminescence intensity (photosynthetic photon flux density) of the sixth maximum peak wavelength 33 is approximately 1.7 (100%), while the luminescence intensity of the fourth maximum peak wavelength 31 is approximately 1.2 (71% (of the luminescence intensity of the sixth maximum peak wavelength 33)). The luminescence intensity of the fifth maximum peak wavelength 32 is approximately 0.7 (41% (of the luminescence intensity of the sixth maximum peak wavelength 33)). The luminescence intensity of the second minimum peak wavelength 34 is approximately 0.3 (17% (of the luminescence intensity of the sixth maximum peak wavelength 33)). The maximum luminescence intensity in the wavelength range of 700 nm or more and 750 nm or less (the wavelength range of far-red light, the fifth wavelength range) is approximately 1.2 (71% (of the luminescence intensity of the sixth maximum peak wavelength 33)) at a wavelength of 700 nm.

[0035] 3, the second LED 40 has a continuous spectrum in the wavelength range of at least 500 nm to 750 nm, and includes a second light-emitting diode 40A. In this embodiment, the second LED 40 emits yellow light with a correlated color temperature of 3000 K, but the correlated color temperature is not limited to this.

[0036] A DC voltage is applied to the second light-emitting diode 40A from the LED substrate 20. The second light-emitting diode 40A lights up and emits light in response to the applied DC voltage. The second light-emitting diode 40A emits light having a seventh maximum peak wavelength 41 in which the emission intensity reaches a maximum peak (maximum) in a wavelength range of 560 nm or more and 600 nm or less (yellow light wavelength range, fourth wavelength range). A yellow-emitting diode is used as the second light-emitting diode 40A.

[0037] The emission spectrum of the second LED 40 will now be described in detail. As shown in Fig. 3, the second LED has a continuous spectrum in the wavelength range of 500 nm to 750 nm. The vertical axis of Fig. 3 represents relative emission intensity, and the horizontal axis represents wavelength (nm).

[0038] More specifically, the seventh maximum peak wavelength 41 is in the wavelength range of 570 nm to 590 nm, and its center wavelength (peak wavelength) is approximately 580 nm.

[0039] As shown in Fig. 4, the emission spectrum of mixed light (light) 50 of the first LED 30 and the second LED 40 will be described. The mixed light 50 has a continuous spectrum in the wavelength range of 420 nm to 750 nm. In this embodiment, the mixed light 50 emits white light with a correlated color temperature of 3750 K. However, the present invention is not limited to this. For example, by changing the output of the first LED 30 and the second LED 40, the correlated color temperature can be changed from 4000 K to 5000 K.

[0040] The mixed light 50 emits light having a first maximum peak wavelength 51 in which the emission intensity reaches its maximum peak (becomes maximum) in a wavelength range of 430 nm or more and 470 nm or less (wavelength range of blue light, first wavelength range), light having a second maximum peak wavelength 52 in which the emission intensity reaches its maximum peak (becomes maximum) in a wavelength range of 530 nm or more and 570 nm or less (wavelength range of green light, second wavelength range), and light having a third maximum peak wavelength 53 in which the emission intensity reaches its maximum peak (becomes maximum) in a wavelength range of 640 nm or more and 680 nm or less (wavelength range of red light, third wavelength range).

[0041] The mixed light 50 further includes light having a first maximum peak wavelength 54 at which the emission intensity reaches a minimum peak (becomes the smallest) in the wavelength range of 560 nm to 600 nm (the wavelength range of yellow light, the fourth wavelength range).

[0042] The first maximum peak wavelength 51 is more specifically in the wavelength range of 440 nm to 460 nm, and its center wavelength (peak wavelength) is approximately 450 nm. The second maximum peak wavelength 52 is more specifically in the wavelength range of 540 nm to 560 nm, and its center wavelength (peak wavelength) is approximately 550 nm. The third maximum peak wavelength 53 is more specifically in the wavelength range of 650 nm to 670 nm, and its center wavelength (peak wavelength) is approximately 660 nm. The first minimum peak wavelength 54 is more specifically in the wavelength range of 570 nm to 590 nm, and its center wavelength (peak wavelength) is approximately 580 nm.

[0043] The emission intensity of the third maximum peak wavelength 53 is approximately 1.5 (100%), while the emission intensity of the first maximum peak wavelength 51 is approximately 0.9 (60% (relative to the emission intensity of the third maximum peak wavelength 53)). The emission intensity of the second maximum peak wavelength 52 is approximately 0.7 (47% (relative to the emission intensity of the third maximum peak wavelength 53)). Furthermore, the emission intensity of the first minimum peak wavelength 54 is approximately 0.6 (40% (relative to the emission intensity of the third maximum peak wavelength 53)).

[0044] Furthermore, the maximum emission intensity in the wavelength range of 700 nm or more and 750 nm or less (the wavelength range of far-red light, the fifth wavelength range) is approximately 1.0 (67% (relative to the emission intensity of the third maximum peak wavelength 53)) at a wavelength of 700 nm.

[0045] In the first LED 30 and the second LED 40, the second minimum peak wavelength 34 and the seventh maximum peak wavelength 41 roughly overlap each other.

[0046] That is, the mixed light 50 from the first LED 30 and the second LED 40 has a spectrum in which the second minimum peak wavelength 34 and the seventh maximum peak wavelength 41 overlap. Therefore, in the mixed light 50, the emission intensity of the first minimum peak wavelength 54 in the wavelength range of 560 nm to 600 nm is greater than the emission intensity of the second minimum peak wavelength 34.

[0047] Specifically, the first minimum peak wavelength 54 of the mixed light 50 corresponds to the second minimum peak wavelength 34 of the first LED 30, but the light emission intensity is increased compared to the first LED 30 alone (0.3 to 0.6 in this embodiment).

[0048] As described above, the mixed light 50 has an emission spectrum with high emission intensity over a wide wavelength range because the second minimum peak wavelength 34 and the seventh maximum peak wavelength 41 overlap, which allows the emitted light to have better color rendering properties than when the first LED 30 and the second LED 40 are used individually.

[0049] Therefore, it is possible to clearly check the condition of plants when checking their growth or harvesting. In other words, light with excellent color rendering makes it easier to notice if there is something wrong with the plant (for example, if you look at a plant under pink light with poor color rendering, it is difficult to notice discoloration or paleness due to disease).

[0050] Here, color rendering is an index that numerically expresses how closely the color of an object illuminated by light is reproduced to that of sunlight, compared to when viewed under sunlight. Excellent color rendering (also called high color rendering) means that the color appearance is close to that when viewed under natural light (sunlight). Color rendering is determined by the JIS color rendering evaluation method, which is based on the evaluation method of the CIE (International Commission on Illumination), and is expressed using the average color rendering index (Ra). The average color rendering index has a maximum value of 100, and the closer to 100 the index is, the better the color rendering is evaluated.

[0051] Here, a case where a plant is grown using the lighting device 1 will be described. Below, the growth condition of lettuce for each light source will be compared. FIG. 5 is a diagram showing the growth condition of leaf lettuce under each light source, FIG. 6 is a diagram showing the growth condition of head lettuce under each light source, and FIG. 7 is a diagram showing the growth condition of sunny lettuce under each light source. FIG. 8 is a diagram showing the morphology of lettuce under each light source, (A) showing the morphology of head lettuce, and (B) showing the morphology of sunny lettuce. Furthermore, FIG. 9 is a diagram showing the emission spectrum of a first comparative light source 60 in the comparative example, and FIG. 10 is a diagram showing the emission spectrum of a second comparative light source 70 in the comparative example.

[0052] The light sources used to compare the growth of lettuce are as shown in Table 1 below.

[0053] [Table 1]

[0054] As shown in Table 1, the PPFD [μmol / s / m 2 The PPFD [μmol / s / m 2 ] is 255.6, the power consumption is 67 [W], and the PPFD [μmol / s / m 2 ] is 172.3 and power consumption is 65[W].

[0055] First, the first comparative light source 60 will be described with reference to Fig. 9. The first comparative light source 60 is a white LED with a correlated color temperature of 5000K. The first comparative light source 60 has a continuous spectrum in the wavelength range of at least 420nm to 750nm, and includes a comparative light emitting diode (not shown) and a comparative phosphor film (not shown). The general color rendering index Ra of the first comparative light source 60 is 80-85.

[0056] The comparative light emitting diode emits light having a first comparative peak wavelength 61 in which the emission intensity reaches a maximum peak (maximum) in the wavelength range of 430 nm or more and 470 nm or less (wavelength range of blue light). As the comparative light emitting diode, a blue light emitting diode is used.

[0057] The comparative phosphor film is formed so as to cover the comparative light emitting diode. After light from the comparative light emitting diode is absorbed by the comparative phosphor film, the comparative light emitting diode emits light having a second comparative peak wavelength 62 at which the emission intensity reaches a maximum peak (maximum) in the wavelength range of 560 nm to 600 nm (the wavelength range of yellow light).

[0058] That is, the first comparison light source 60 emits light having a first comparison peak wavelength 61 and light having a second comparison peak wavelength 62 .

[0059] Next, the second comparative light source 70 will be described with reference to Fig. 10. The second comparative light source 70 is a three-band fluorescent lamp that emits light having a third comparative peak wavelength 71 in the wavelength range of 440 nm to 460 nm (wavelength range of blue light) at which the emission intensity reaches a maximum peak (maximum), light having a fourth comparative peak wavelength 72 in the wavelength range of 530 nm to 570 nm (wavelength range of green light) at which the emission intensity reaches a maximum peak (maximum), and light having a fifth comparative peak wavelength 73 in the wavelength range of 600 nm to 640 nm (wavelength range of red light) at which the emission intensity reaches a maximum peak (maximum).

[0060] The luminescence intensity (photosynthetic photon flux density) of the fourth peak wavelength for comparison 72 is approximately 3.8 (100%), while the luminescence intensity of the third peak wavelength for comparison 71 is approximately 1.2 (31% (relative to the luminescence intensity of the fourth peak wavelength for comparison 72)). In addition, the luminescence intensity of the fifth maximum peak wavelength 73 is approximately 2.7 (71% (relative to the luminescence intensity of the fourth peak wavelength for comparison 72)).

[0061] Next, we will explain the growing environment for lettuce grown using each light source shown in Table 1. In this embodiment, the lettuce used were three varieties: leaf lettuce (Green Jacket), head lettuce (Cisco (registered trademark)), and sunny lettuce (Red Fire).

[0062] The lettuce described above was grown using hydroponic cultivation for a specified number of days. Hydroponic cultivation is a method of cultivating plants using water and a nutrient solution without using soil. The nutrient solution used was OAT-A manufactured by OAT Agrio Co., Ltd.

[0063] The light sources are installed at a height of approximately 280 mm from the hydroponic containers, and the room temperature is set to 18°C to 22°C and the humidity to approximately 50%.

[0064] The light source was then cycled between 12 hours on and 12 hours off, and the mass was measured until the specified number of days had passed. The mass was measured with the roots attached, and the number of plants grown was reduced as the plants grew (16 plants → 8 plants → 4 plants → 3 plants).

[0065] Next, the results of the experiment conducted under the above-mentioned conditions will be explained using Table 2 below and Figures 5 to 8. The masses below are the average masses of three strains.

[0066] [Table 2]

[0067] As shown in Table 2 and Figure 5, 35 days after sowing, the mass of the leaf lettuce grown using lighting device 1 was 173.4 [g], the mass of the leaf lettuce grown using the first comparative light source 60 was 151.7 [g], and the mass of the leaf lettuce grown using the second comparative light source 70 was 80.6 [g].

[0068] As shown in Table 2 and Figure 6, 65 days after sowing, the mass of the head lettuce grown using lighting device 1 was 558.6 [g], the mass of the head lettuce grown using first comparative light source 60 was 506.8 [g], and the mass of the head lettuce grown using second comparative light source 70 was 360.4 [g].

[0069] Furthermore, as shown in Table 2 and Figure 7, 52 days after sowing, the mass of sunny lettuce grown using lighting device 1 was 239.2 [g], the mass of sunny lettuce grown using the first comparative light source 60 was 208.7 [g], and the mass of sunny lettuce grown using the second comparative light source 70 was 138.6 [g].

[0070] These lettuces were grown for approximately 1-2 months after planting. In general, the harvested mass of leaf lettuce is approximately 150g-200g, that of head lettuce is approximately 500g, and that of sunny lettuce is approximately 100g-200g.

[0071] In other words, when the lighting device 1 is used, the mass of the lettuce at harvest is greater than when the other light sources 60 and 70 are used. In other words, the period until the lettuce reaches a mass that is suitable for harvesting is shortened by using the lighting device 1. This allows the lettuce to be harvested in a shorter period of time, so that a larger amount of lettuce can be harvested efficiently in a certain period of time compared to when other light sources are used. In addition, with regard to power consumption, when the lighting device 1 is used, a larger mass of lettuce can be harvested in a shorter period of time while consuming the same amount of power, so that the plant (lettuce) can be grown efficiently while suppressing power consumption.

[0072] As shown in Figure 8(A), the heads of head lettuce formed normally (all three plants) and no tip burn was observed when using lighting device 1. The heads of head lettuce formed small (all three plants) and no tip burn was observed when using first comparative light source 60. The heads of head lettuce formed normally (all three plants) and no tip burn was observed when using second comparative light source 70.

[0073] Furthermore, as shown in FIG. 8(B), the reddish-brown color of sunny lettuce was the darkest among the light sources used by the lighting device 1, and was lightest with the first comparative light source 60 and the second comparative light source 70.

[0074] In other words, when the lighting device 1 was used, the morphology (head formation, tip burn) was more normal than when the other light sources 60 and 70 were used. In other words, when the lighting device 1 is used, it is possible to prevent the head from becoming small and the occurrence of tip burn when growing plants.

[0075] In this embodiment, the emission intensity of the third maximum peak wavelength 53 is 40% of the emission intensity of the first minimum peak wavelength 54. In other words, by mixing the light of the first LED 30 and the second LED 40, the emission intensity of the yellow light can be made greater than the second minimum peak wavelength 34.

[0076] Furthermore, in this embodiment, light containing far-red light that affects plant morphogenesis is emitted at an emission intensity that is 67% of the emission intensity of the second maximum peak wavelength 52. Maintaining sufficient emission intensity of far-red light allows the plant (lettuce) to grow more quickly.

[0077] In this embodiment, the second LED 40 emits light having a seventh maximum peak wavelength 41 in the wavelength range of yellow light, but also includes red light (wavelength range of 600 nm to 640 nm) and far-red light (wavelength range of 700 nm to 750 nm). These lights (red light and far-red light) affect the morphogenesis of plants, but if the amount of light (emission intensity) provided is too large (high), the plants will become elongated.

[0078] However, in this embodiment, it is possible to suppress the elongation by setting the emission intensity of the first minimum peak wavelength 54 to be 20% or more and 100% or less of the emission intensity of the second maximum peak wavelength 52. Furthermore, the range of the emission intensity is not limited to the above-mentioned range, and for example, the emission intensity of the first minimum peak wavelength 54 may be 20% or more and 60% or less of the emission intensity of the second maximum peak wavelength 52, or the emission intensity of the first minimum peak wavelength 54 may be 35% or more and 45% or less of the emission intensity of the second maximum peak wavelength 52.

[0079] Furthermore, in this embodiment, in consideration of the aforementioned elongated growth, the maximum emission intensity in the wavelength range of 700 nm to 750 nm (far-red) is set to 30% to 70% of the emission intensity of the second maximum peak wavelength 52, thereby enabling the plant (lettuce) to grow faster while suppressing elongated growth. Furthermore, the range of emission intensity is not limited to the above-mentioned range, and for example, the maximum emission intensity in the wavelength range of 700 nm to 750 nm (far-red) may be 60% to 70% of the emission intensity of the second maximum peak wavelength 52.

[0080] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications (for example, modifications to the correlated color temperature of the combined LEDs) can of course be made. [Explanation of symbols]

[0081] 1. Lighting equipment 10…Case 11...Light diffusion section 12...Electrode 20...LED board 30…First LED 31...Fourth maximum peak wavelength 32...5th maximum peak wavelength 33...6th maximum peak wavelength 34...Second minimum peak wavelength 40...Second LED 41...7th maximum peak wavelength 50…Mixed light 51...First maximum peak wavelength 52...Second maximum peak wavelength 53...Third maximum peak wavelength 54...First minimum peak wavelength

Claims

1. An illumination device that emits light having a continuous spectrum at least in a wavelength range of 420 nm to 750 nm, the light has a first maximum peak wavelength that is a maximum peak in a first wavelength range of 430 nm or more and 470 nm or less, a second maximum peak wavelength that is a maximum peak in a second wavelength range of 530 nm or more and 570 nm or less, and a third maximum peak wavelength that is a maximum peak in a third wavelength range of 640 nm or more and 680 nm or less, The emission intensity of the third maximum peak wavelength is greater than the emission intensity of the first maximum peak wavelength. Lighting equipment.

2. 10. The lighting device according to claim 1, In the spectrum of the light, the emission intensity of the third maximum peak wavelength is greater than the emission intensity of the second maximum peak wavelength. Lighting equipment.

3. 10. The lighting device according to claim 1, In the spectrum of the light, the emission intensity of a minimum peak wavelength that is the minimum peak in a fourth wavelength range of 560 nm to 600 nm is 20% to 100% of the emission intensity of the second maximum peak wavelength. Lighting equipment.

4. 4. The lighting device according to claim 3, In the spectrum of the light, the emission intensity of the minimum peak wavelength in the fourth wavelength range is 20% or more and 60% or less of the emission intensity of the second maximum peak wavelength. Lighting equipment.

5. 5. The lighting device according to claim 4, In the spectrum of the light, the emission intensity of the minimum peak wavelength in the fourth wavelength range is 35% or more and 45% or less of the emission intensity of the second maximum peak wavelength. Lighting equipment.

6. 10. The lighting device according to claim 1, In the spectrum of the light, the maximum emission intensity in a fifth wavelength range of 700 nm to 750 nm is 30% to 70% of the emission intensity of the second maximum peak wavelength. Lighting equipment.

7. 7. The lighting device according to claim 6, In the spectrum of the light, the maximum emission intensity in the fifth wavelength range is 60% or more and 70% or less of the emission intensity of the second maximum peak wavelength. Lighting equipment.

8. 10. The lighting device according to claim 1, the light is a mixed light of a first LED having a continuous spectrum in the wavelength range of 420 nm to 750 nm and a second LED having a continuous spectrum in the wavelength range of 500 nm to 750 nm, the first LED has a third maximum peak wavelength that is a maximum peak in the first wavelength range and is different from the first maximum peak wavelength, a fourth maximum peak wavelength that is a maximum peak in a wavelength range of 500 nm or more and 540 nm or less, and a fifth maximum peak wavelength that is a maximum peak in the third wavelength range and is different from the second maximum peak wavelength, The second LED has a sixth maximum peak wavelength that is the maximum peak in the second wavelength range. Lighting equipment.

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