Blades for wind turbines, wind turbines and buildings

Abstract

The blade (1) for a wind power generator has a surface covered with a reflective material layer (12) made of a light-reflecting material that reflects light such that when light is incident on an insect's compound eye, at least three types of photoreceptors present in the ommatidium that make up the compound eye contain visual pigments with different absorption wavelength bands, which are the wavelength bands of light that the photoreceptors absorb, and the difference in light intensity in the absorption wavelength bands of the visual pigments contained in each of the multiple types of photoreceptors that make up part of the ommatidium of the insect's compound eye become excited when they absorb light, is equal to or less than a predetermined intensity difference threshold.

Description

[Technical Field]

[0001] The present invention relates to a plate for a wind turbine generator, a wind turbine generator, and a building. [Background technology]

[0002] A lighting system has been proposed that includes two types of light sources that emit light with different spectral power distributions, and by setting the spectral power distribution of the light emitted from one of the light sources to have a higher insect attracting effect than that of the other light source, it is possible to attract and retain insects to one of the two light sources, thereby reducing the discomfort caused to people near the other light source (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2017-509321 Summary of the Invention [Problem to be solved by the invention]

[0004] A wind turbine typically includes a tower, blades attached to the top of the tower, and a generator that generates electricity using rotational power generated by the blades rotating when the wind strikes them. In such wind turbines, a decrease in the blade rotation speed leads to a corresponding decrease in the amount of electricity generated. It has been reported that insects are attracted to the blades and attach to them, increasing the air resistance of the blades and reducing rotational efficiency, resulting in a decrease in power generation. Furthermore, wind turbines are often installed in natural areas with relatively good wind conditions throughout the year. It has also been pointed out that insects and flying animals that feed on insects living near the installation site of the wind turbine are attracted to the rotating blades of the wind turbine and die when they hit the blades, disrupting the ecological balance of the installation site.

[0005] The present invention has been made in consideration of the above-mentioned reasons, and aims to provide a blade for a wind turbine generator, a wind turbine generator, and a building that can maintain power generation and protect the environment by making it difficult for insects to be attracted. [Means for solving the problem]

[0006] In order to achieve the above object, the blade for a wind turbine according to the present invention comprises: When light is incident on an insect's compound eye, at least three types of photoreceptors present in the ommatidium that makes up the compound eye contain visual pigments that have different absorption wavelength bands, which are the wavelength bands of light that they absorb, and the surface is covered with a reflective material layer made of a light-reflecting material that reflects light such that the difference in light intensity in the absorption wavelength bands of the visual pigments contained in each of the multiple types of photoreceptors that make up part of the ommatidium of the insect's compound eye that become excited when they absorb light is below a predetermined intensity difference threshold. [Effects of the Invention]

[0007] According to the present invention, the surface is covered with a reflective material layer made of a light-reflecting material that reflects light such that, when the light is incident, the difference in light intensity in the absorption wavelength bands of the visual pigments contained in each of the multiple types of photoreceptor cells that make up part of the insect's eye is equal to or less than a predetermined intensity difference threshold. This makes it difficult for insects to be attracted to the wind turbine blades, thereby suppressing insect adhesion to the turbine blades and maintaining the power generation capacity of the wind turbine. Furthermore, suppressing insect adhesion to the turbine blades helps preserve the environment where the wind turbine is installed. [Brief explanation of the drawings]

[0008] [Figure 1A] FIG. 1 is a schematic diagram showing the multiple image eyes of an insect. [Figure 1B] FIG. 1 is a schematic diagram showing the overlapping eyes of an insect. [Figure 2A] Schematic diagram of an insect ommatidium. [Figure 2B]FIG. 2B is a cross-sectional view of an insect ommatidium taken along line AA in FIG. 2A. [Figure 3] FIG. 1 is a diagram showing the absorption wavelength bands of visual pigments contained in each of the photoreceptor cells that make up part of an insect's eye. [Figure 4A] This is a photo of the appearance of morning glory. [Figure 4B] FIG. 1 is a diagram showing the reflected light spectrum of the petals of Mirabilis mirabilis. [Figure 5] FIG. 1 is a diagram showing the reflected light spectrum of a leaf portion of Mirabilis mirabilis. [Figure 6A] This is a photo of the appearance of a cuckoo. [Figure 6B] FIG. 1 is a diagram showing the reflected light spectrum of the petals of a lesser cuckoo flower. [Figure 7] FIG. 1 is a diagram showing the reflected light spectrum of the leaves of a lesser cuckoo. [Figure 8] FIG. 1 is a diagram showing the optical spectrum of light that has an insect attracting effect. [Figure 9A] This is a photo of the exterior of a white magnolia tree. [Figure 9B] FIG. 1 is a diagram showing the reflected light spectrum of the petals of a white magnolia tree. [Figure 10] Schematic diagram of an insect's compound eye. [Figure 11A] Schematic diagram of an insect ommatidium. [Figure 11B] FIG. 10 is a schematic diagram showing a case where the distance between the target and the eye is relatively short. [Figure 11C] FIG. 10 is a schematic diagram showing a case where the distance between the target and the eye is relatively long. [Figure 12A] 1 is a schematic diagram of a wind turbine generator according to an embodiment. [Figure 12B] 1 is a cross-sectional view of a portion of a blade for a wind turbine generator according to an embodiment. [Figure 13A] 10A and 10B are diagrams illustrating the optical spectra of light emitted from reflecting members according to examples and comparative examples. [Figure 13B] FIG. 10 is a diagram showing the number of insects attached to the reflective members according to the example and the comparative example. [Figure 14]FIG. 10 is a diagram showing a schematic configuration of a wind power generation system according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of the present invention will be described below with reference to the accompanying drawings. A blade for a wind turbine according to this embodiment includes a reflecting member that reflects light such that multiple types of photoreceptor cells constituting part of an insect's eye that are excited when light is absorbed by the visual pigment and that have different absorption wavelength bands, which are wavelength bands of light that the insect absorbs, are all excited to approximately the same extent, or a light-emitting member that emits light that excites all of the multiple types of photoreceptor cells to approximately the same extent.

[0010] Here, we will explain the structure of insect eyes, which is the premise of this invention. Insects with compound eyes are divided into diurnal and nocturnal insects. Diurnal insects have a compound eye CE1 formed by a group of multiple ommatidia, as shown in FIG. 1A, for example. On the other hand, nocturnal insects have a double eye CE2 including a transparent layer CL, as shown in FIG. 1B, for example. As shown in FIG. 1A, the compound eye CE1 has multiple corneas CU, one cone CR for each of the multiple corneas CU, photoreceptor cells RE on the side of the cone CR opposite the cornea CU, and an optic nerve NO continuous with the photoreceptor cells RE. On the other hand, as shown in FIG. 1B, the multiple-image eye CE1 includes a plurality of corneas CU, one cone CR for each of the plurality of corneas CU, photoreceptor cells RE spaced from the cone CR on the side of the cone CR opposite the cornea CU, an optic nerve NO connected to the photoreceptor cells RE, and a transparent layer CL interposed between the cone CR and the photoreceptor cells RE. The photoreceptor cells RE are arranged to surround rhabdoms RH, which are photoreceptor sites located along the optical axis of a lens system consisting of a pair of corneas CU and cones CR. The photoreceptor cells RE each contain a visual pigment with a different absorption wavelength band, which is the wavelength band of light they absorb. For example, as shown in FIG. 2A, the photoreceptor cells RE_L, RE_M, and RE_S are arranged so that their visual pigment-containing portions P_L, P_M, and P_S, each containing a visual pigment, are adjacent to each other, thereby forming a rhabdom RH composed of the visual pigment-containing portions P_L, P_M, and P_S. Note that L, M, and S represent long wavelength, medium wavelength, and short wavelength, respectively. The focal length of the ommatidium is several centimeters to 50 cm, and insects cannot change this distance. Therefore, if an object is located at a distance greater than the focal length of the ommatidium, an image of the object cannot be formed on the rhabdome RH. Furthermore, if the object has multiple colors, the light corresponding to each color emitted from the object will be mixed and incident on the rhabdome RH. Meanwhile, insects have high temporal resolution and can spatially perceive wind turbine blades that rotate at speeds that the human eye cannot perceive.

[0011] As shown in Figure 2B, the rhabdome RH is formed adjacent to the lens system consisting of the cornea CU and the cones CR. Each of these visual pigment-containing regions P_L, P_M, and P_S has a structure in which numerous microvilli protrude, and these microvilli contain visual pigments. The rhabdome RH has a higher refractive index than the rest of the visual pigment-containing regions P_L, P_M, and P_S of the photoreceptor cells RE, and functions as an optical waveguide for light entering the rhabdome RH from the lens system consisting of the cornea CU and the cones CR. Therefore, as shown by the arrow Li in Figure 2B, light entering the rhabdome RH from the lens system consisting of the cornea CU and the cones CR propagates within the rhabdome RH. Note that some insects IN have overlapping eyes, in which a transparent layer is interposed between the lens system consisting of multiple corneas CU and multiple cones CR and the photoreceptor cells RE.

[0012] Furthermore, the photoreceptor cells RE_L, RE_M, and RE_S each have a visual pigment-containing portion P_L, P_M, and P_S, respectively, which contain visual pigments with different absorption wavelength bands, which are wavelength bands of light that they absorb. In the photoreceptor cell RE_L, for example, as shown by the curve S_L in Fig. 3, a visual pigment-containing portion P_L containing a visual pigment with an absorption wavelength band of 450 nm to 700 nm is formed. In the photoreceptor cell RE_M, for example, as shown by the curve S_M in Fig. 3, a visual pigment-containing portion P_M containing a visual pigment with an absorption wavelength band of 350 nm to 550 nm is formed. In addition, in the photoreceptor cell RE_S, for example, as shown by the curve S_S in Fig. 3, a visual pigment-containing portion P_S containing a visual pigment with an absorption wavelength band of 300 nm to 400 nm is formed. The RE_L photoreceptor cells are excited when the visual pigment absorbs light in the wavelength range of 450 nm to 700 nm, and the RE_M photoreceptor cells are excited when the visual pigment absorbs light in the wavelength range of 350 nm to 550 nm.The RE_L photoreceptor cells are also excited when the visual pigment absorbs light in the wavelength range of 450 nm to 700 nm.

[0013] Based on the above, the inventors investigated the reflected light spectra of flowers that attract insects in nature. When the reflected light spectra were measured for light reflected from five locations on the petals of a Mirabilis flower (Figure 4A), reflected light spectra S11, S12, S13, S14, and S15 were obtained, as shown in Figure 4B. The intensity in the wavelength range of 500 to 600 nm was lower than the intensity in the wavelength ranges around 400 nm and 650 nm or higher. Furthermore, when the reflected light spectra were measured for light reflected from four locations on the leaves of Mirabilis flower (Figure 4A), reflected light spectra S16, S17, S18, and S19 were obtained, as shown in Figure 5. These spectra have a lower contrast between the intensity in the wavelength range of 500 to 600 nm and the intensity in the wavelength ranges around 400 nm and 650 nm or higher, compared to the petals. Furthermore, when the reflected light spectrum was measured for light reflected from each of five locations on the petals of the lesser cuckoo shown in Figure 6A, reflected light spectra S21, S22, S23, S24, and S25 were observed, as shown in Figure 6B, in which the intensity in the wavelength region around 550 nm was lower than the intensity in the wavelength regions around 450 nm and 650 nm or above. Furthermore, when the reflected light spectrum was measured for each of six locations on the leaves of the lesser cuckoo shown in Figure 6A, reflected light spectra S26, S27, S28, S29, S30, and S31 were observed, as shown in Figure 7, in which the contrast between the intensity in the wavelength region around 550 nm and the intensity in the wavelength regions around 450 nm and 650 nm or above was lower than that of the petals. These results indicate that insects are attracted to flowers that reflect light with a reflected light spectrum that has peaks on both the long and short wavelength sides, in other words, a valley where the intensity is low. Specifically, we found that insects are more likely to be attracted to flowers that reflect light with a reflected light spectrum in which the sum of the intensities of the components corresponding to the absorption wavelength band of 300 nm or more and 400 nm or less of the visual pigment contained in photoreceptor cell RE_S and the sum of the intensities of the components corresponding to the absorption wavelength band of 450 nm or more and 700 nm or less of the visual pigment contained in photoreceptor cell RE_L are greater than the sum of the intensities of the components corresponding to the absorption wavelength band of 350 nm or more and 550 nm or less of the visual pigment contained in photoreceptor cell RE_M.Furthermore, since insects tend to be attracted to the petals of flowers more than the leaves, it was found that the greater the contrast in intensity, the more likely insects are to be attracted.

[0014] From this, the inventors have found that a light source that emits light having a spectral spectrum in which the sum of the intensities of the components corresponding to the absorption wavelength band of 300 nm to 400 nm of the visual pigment contained in the photoreceptor cell RE_S and the sum of the intensities of the components corresponding to the absorption wavelength band of 450 nm to 700 nm of the visual pigment contained in the photoreceptor cell RE_L are greater than the sum of the intensities of the components corresponding to the absorption wavelength band of 350 nm to 550 nm of the visual pigment contained in the photoreceptor cell RE_M. That is, as shown in Figure 8, the inventors have found that a light reflective material that reflects or a light source that emits light having a spectral spectrum S51 with intensity peaks in the wavelength bands of 300 nm to 400 nm and 450 nm to 700 nm and a valley where the intensity drops in the wavelength band of 350 nm to 550 nm has a high insect attracting effect.

[0015] Furthermore, as shown in Fig. 9A, in petals that appear white to humans, as shown in reflected light spectra S41 to S47 in Fig. 9B, there is almost no reflection below 400 nm, and the reflection increases sharply from the wavelength band above 400 nm, and remains high and approximately constant from 400 nm to the longer wavelength side, and it has been found that light reflective materials or light sources that emit such light that appear white to humans and have no reflection below 400 nm also have a high insect attracting effect. In other words, it has been found that light reflective materials or light sources that emit light that reflect light having the spectral spectra S51 and S52 in Fig. 8 have a high insect attracting effect.

[0016] In multiple-image or overlapping-image eyes, light incident from a target relatively far from the eye enters one or a few ommatidia. In the case of multiple-image eyes, the visual field angle of each ommatidia is approximately 1 to 2 degrees, and one or a few ommatidia can receive light. In the case of overlapping-image eyes, light incident on multiple ommatidia is focused by the cornea and cones, passes through the stratum lucidum (CL), and enters one or a few rhabdoms. In this case, if the rhabdoms are formed from photoreceptors that excite light in different wavelength bands, information about the wavelength of light is retained, allowing discrimination based on the difference in excitation of different photoreceptors. However, so-called spatial information, such as the shape of the target or the distance to the target, is lost. For example, as shown in Figure 10, the spatial discrimination of insects is determined by both the angular sensitivity A11 of the ommatidia and the inter-ommatidia angle A12. As mentioned above, each insect ommatidium consists of a lens system consisting of a cornea and cones, and a rhabdom, a photoreceptor site where photoreceptors project near the optical axis. As shown in Figure 11A, the visual field angle of each ommatidium is narrow, approximately 1 to 2 degrees. As shown in Figure 11B, when an insect is close to a flower, multiple ommatidium individually receive light, allowing it to perceive spatial information, distinguish the flower's shape, and enhance wavelength discrimination. In other words, for targets close to the insect, shape information and wavelength discrimination information can be acquired. On the other hand, as shown in Figure 11C, when the insect moves away from the flower, only one or a few ommatidium can perceive light due to the influence of the ommatidial angular sensitivity A11 and the interommatidial angle A12. As a result, shape and distance information disappear. In other words, for targets far away from the insect, the visible range is determined by the angular sensitivity A11 and interommatidial angle A12 of each ommatidium. In multiple-image eyes, only one or at most a few rhabdoms of an ommatidia receive light, so shape information is lost. In addition, in multiple-image eyes, light incident on the corneas of many ommatidia is focused on the rhabdom of a single ommatidia. Since that single rhabdom receives light from the outside world, shape information is lost. To survive and distinguish targets from backgrounds in the absence of shape information, insects are thought to have evolved to distinguish targets using wavelength contrast information, i.e., spectral spectra with valleys.From this, it is highly likely that flowers that are effective in attracting insects stabilize information acquisition for insects by reflecting light with a wavelength-dependent reflected light spectrum as described above, that is, light with contrast in intensity due to differences in wavelength (see Figure 8). In other words, due to the structure of their eyes, insects cannot distinguish the shape of targets that are located relatively far away, and it is thought that the waveform information that enters the ommatidia, that is, the information on the optical spectrum, triggers the attracting behavior.

[0017] As shown in FIG. 12A , a wind power generator 100 according to this embodiment typically includes three wind power generator blades 1, a rotor 2 (nacelle) that rotates and drives the wind power generator blades 1, and a support 3 (tower) that supports the rotor 2. The wind power generator blade 1 was invented based on the findings regarding the insect attraction effect of an optical spectrum having the aforementioned so-called valley. Specifically, as shown in FIG. 12B , the surface of the wind power generator blade 1 is covered with a reflective material layer 12 made of a light-reflecting material that reflects light having an optical spectrum that does not have the aforementioned valley. In other words, the wind power generator blade 1 has a surface covered with a reflective material layer 12 made of a light-reflecting material that reflects incident light such that the difference in light intensity in the absorption wavelength bands of the visual pigments contained in multiple types of photoreceptor cells that constitute part of the insect's eye and are excited when the visual pigment absorbs light is equal to or less than a predetermined intensity difference threshold. It is preferable that the difference in intensity between each wavelength of the spectrum of the light emitted from the reflective material layer 12 is 25% or less. The light-reflecting material forming the light-reflecting material layer 12 may be not only a paint that reflects light having the above-mentioned spectrum, but also a metal or resin film that reflects light having the above-mentioned spectrum.

[0018] Here, we will describe the results of an experiment comparing the number of insects attached to reflective members according to an example of the present invention and a comparative example (see Figures 13A and 13B). The reflective members according to the example and comparative example were fabricated by coating the surface of a 33.3 cm × 24.4 cm canvas with paint made from various light-reflecting materials. The light-reflecting material used for the reflective members according to comparative examples 1 and 2 was a material with a reflectance spectrum in which the reflectance drops sharply around 400 nm, as shown in Figure 13A. Comparative example 1 is a paint used in current wind power generation facilities. Comparative example 2 is a material with a spectral curve similar to the reflectance spectrum of white flowers. On the other hand, the light-reflecting material used for the reflective members according to examples 1 to 4 of the present invention was a material with a reflectance spectrum in which the difference in reflectance at each wavelength was 25% or less, as shown in Figure 13A. In this experiment, the reflective members according to the comparative example and example were left on the roof of a Hamamatsu University School of Medicine building for four days, and the number of insects attached to the surface of the reflective member was counted 10 times, and the average values ​​of the 10 measurements were compared.

[0019] The number of insects attached to the reflective members of the Example and Comparative Example is shown in Figure 13B. As shown in Figure 13B, it was found that the number of insects attached to the reflective member of the Example was reduced by at least 40% compared to the number of insects attached to the reflective member of the Comparative Example. From these results, it was found that the reflective member of the Example was more effective in reducing insect attachment than the reflective member of the Comparative Example. In other words, it was found that it is preferable that the intensity difference at each wavelength in the spectral spectrum of light reflected by the reflective member be 25% or less.

[0020] As described above, the surface of the wind turbine blade 1 according to this embodiment is covered with the reflective material layer 12 made of a light-reflecting material that reflects light such that, when the light is incident, the difference in light intensity in the absorption wavelength bands of the visual pigments contained in the multiple types of photoreceptor cells that make up part of the insect's eye is equal to or less than a preset intensity difference threshold. This makes it difficult for insects to be attracted to the wind turbine blade 1, thereby suppressing the attachment of insects to the wind turbine blade 1 and maintaining the amount of power generated by the wind turbine 100. Furthermore, suppressing the attachment of insects to the wind turbine blade 1 helps preserve the environment where the wind turbine 100 is installed.

[0021] Although the embodiments of the present invention have been described above, the present invention is not limited to the configurations of the above-described embodiments. For example, as in the wind power generation system shown in FIG. 14, the insect-attracting light source 200 and the reflective member 300 may be located away from the location where the wind power generation device 2100 including the wind power generation device blades 2001 is installed, thereby preventing insects from approaching the wind power generation device blades. Furthermore, the insect-attracting light source 200 may emit light having a spectrum with intensity peaks in the wavelength bands of 300 nm to 400 nm and 450 nm to 700 nm, and a valley where the intensity drops in the wavelength band of 350 nm to 550 nm, as shown in FIG. 8. Furthermore, the insect-attracting reflective member 300 may reflect light having a spectrum with intensity peaks in the wavelength bands of 300 nm to 400 nm and 450 nm to 700 nm, and a valley where the intensity drops in the wavelength band of 350 nm to 550 nm, as shown in FIG. 8.

[0022] In this case, during the day, the wind power generator blades 2001 reflect sunlight relatively evenly across the entire wavelength band from 300 nm to 700 nm, making it difficult for insects to detect the presence of the wind power generator blades 2001 and therefore less likely to be attracted to the wind power generator blades. Meanwhile, the reflective member 300 reflects light that attracts insects, so that the insects are drawn to the reflective member 300. Meanwhile, at night, the wind power generator blades 2001 emit light that is relatively flat across the entire wavelength band from 300 nm to 700 nm, making it difficult for insects to detect the presence of the wind power generator blades 2001 and therefore less likely to be attracted to the wind power generator blades 2001. Meanwhile, the light source 200 emits light that attracts insects, so that the insects are attracted to the light source 200. In this way, according to this modification, it is possible to prevent insects from approaching the wind power generator blades 2001.

[0023] In the wind turbine generator according to the embodiment, a marker light may be installed at the tip of the support pole 3. In this case, it is preferable that the marker light emits light having a spectrum in which the intensity gradually increases toward longer wavelengths in the wavelength band of 300 nm or more and 640 nm or less, and the rate of increase in intensity with respect to wavelength is approximately constant.

[0024] In addition, the exterior wall of a building may have a surface covered with a reflective material layer made of a light-reflecting material that reflects light such that when light is incident on the insect, the difference in light intensity in the absorption wavelength bands of the visual pigments contained in each of multiple types of photoreceptor cells that make up part of the eye of the insect that contains visual pigments with different absorption wavelength bands, which are wavelength bands of light that the insect absorbs, is equal to or less than a predetermined intensity difference threshold.

[0025] Although the embodiments and modifications of the present invention have been described above, the present invention is not limited to these. The present invention includes any combination of the embodiments and modifications, and any combination to which appropriate modifications have been made.

[0026] This application is based on Japanese Patent Application No. 2024-165450, filed on September 24, 2024. The entire specification, claims and drawings of Japanese Patent Application No. 2024-165450 are incorporated herein by reference. [Industrial Applicability]

[0027] The present invention is suitable for use as a blade for a wind turbine generator or a wind turbine generator for preventing damage caused by insects. [Explanation of symbols]

[0028] 1, 2001: Blade for wind power generator, 2: Rotor (nacelle), 3: Support (tower), 100, 2100: Wind power generator, 200: Light source, 300: Reflecting member, CE1: Contour eye, CE2: Double eye, CL: Transparent layer, CR: Cone, CU: Cornea, NO: Optic nerve, P_L, P_M, P_S: Parts containing visual pigment, RE, RE_L, RE_M, RE_S: Photoreceptor cells, RH: Rhabdomon

Claims

1. When light is incident on the insect's compound eye, at least three types of photoreceptors present in the ommatidium constituting the compound eye contain visual pigments with different absorption wavelength bands, which are wavelength bands of light that they absorb, and the surface is covered with a reflective material layer made of a light-reflecting material that reflects light such that the difference in light intensity in the absorption wavelength bands of the visual pigments contained in each of the multiple types of photoreceptors constituting part of the ommatidium of the insect's compound eye that become excited when light is absorbed is equal to or less than a predetermined intensity difference threshold. Blades for wind turbines.

2. The light reflected by the light-reflecting material has a spectrum in which the difference in light intensity at different wavelengths is maximum at 25% or less in a wavelength band of 300 nm or more and 700 nm or less. The blade for a wind turbine generator according to claim 1.

3. A wind power generation device that generates electricity by rotating wind power generation device blades, The blade for the wind turbine generator is When light is incident on the insect's compound eye, at least three types of photoreceptors present in the ommatidium constituting the compound eye contain visual pigments with different absorption wavelength bands, which are wavelength bands of light that they absorb, and the surface is covered with a reflective material layer made of a light-reflecting material that reflects light such that the difference in light intensity in the absorption wavelength bands of the visual pigments contained in each of the multiple types of photoreceptors constituting part of the ommatidium of the insect's compound eye that become excited when light is absorbed is equal to or less than a predetermined intensity difference threshold. Wind power generation equipment.

4. When light is incident on the insect's compound eye, at least three types of photoreceptors present in the ommatidium constituting the compound eye contain visual pigments with different absorption wavelength bands, which are wavelength bands of light that they absorb, and the surface is covered with a reflective material layer made of a light-reflecting material that reflects light such that the difference in light intensity in the absorption wavelength bands of the visual pigments contained in each of the multiple types of photoreceptors constituting part of the ommatidium of the insect's compound eye that become excited when light is absorbed is equal to or less than a predetermined intensity difference threshold. building.

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