JP2015028844A - Illumination method using light-emitting diode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide light-emitting diode lighting that can be easily manufactured by virtue of as simple a structure as possible and that has uniform wavelength distribution.SOLUTION: A fluorescent material layer is formed of a plurality of different fluorescent material spots. Mutual overlapping of the fluorescent material layers is prevented to increase efficiency of light absorption and light emission. Additionally, each fluorescent material spot is formed in a sufficiently minute size in comparison with a distance from each fluorescent material spot to an illumination object and an area of a light-emitting diode so that illumination with uniform wavelength distribution can be given to the illumination object.

Description

  The present invention relates to a lighting method realized by combining a light emitting diode and a phosphor having a property of being excited and emitting light.

  Since the 1990s, the manufacturing technology of light-emitting diodes has continued to advance dramatically, and the realization of blue light-emitting diodes and white light-emitting diodes using them have also been realized, and they are widely used not only for display but also for lighting. It was. In particular, in recent years, with the growing awareness of the problems of nuclear power plants, the use of light-emitting diodes with low power consumption and long life characteristics for lighting has become very active.

  The most common white illumination is mainly used for illumination, and methods for realizing the white color are a combination of light emitting diodes of three primary colors of blue, green and red, and a blue light emitting diode and a complementary color of blue. A typical method is to combine yellow phosphors. The former has excellent color reproducibility because it has three primary color light sources, and is mainly used for color displays, while the latter requires only a single color light emitting diode and can be realized with a very inexpensive and simple structure. , Mainly used for lighting.

  The inventors have devised a lighting method excellent in uniformity and durability by combining a light-emitting diode and a diffuser plate containing a phosphor excited and emitted by the light-emitting diode in JP2011-204406A.

  The above-described invention is mainly intended to make the light quantity distribution of the light emitting diodes uniform, and thus has a configuration in which one kind of light emitting diode, one kind of phosphor and a diffusion plate are combined. In order to actually use it for illumination, not only the uniformity of the light amount but also the wavelength distribution becomes an important factor. In principle, the emission spectrum of light-emitting diodes has a narrow wavelength distribution, which is very different from sunlight and natural light. Therefore, in order to realize illumination close to these characteristics, not only the light intensity distribution but also the uniformity of the wavelength distribution is required. This is because it is necessary to consider.

  As an example of realizing such uniform wavelength distribution, there is a method disclosed in Japanese Patent Application Laid-Open No. 2012-77289. The method described therein is characterized in that a plurality of phosphor layers that emit light in each wavelength band are formed in order to compensate for components in a plurality of wavelength bands that are insufficient with white light emitting diodes. According to this method, a light emitting diode having a relatively uniform wavelength distribution close to sunlight or natural light can be realized in one package.

JP2011-204406 JP2012-77289

  According to the method of Patent Document 2, a uniform light emitting element close to sunlight or natural light can be realized by using a light emitting diode, but there is a problem that the structure is complicated and it is difficult to reduce the cost. In addition, the light emitted from the phosphor layer close to the light-emitting diode is absorbed by the other phosphor layers, and the luminous efficiency is reduced. To avoid this, the combination of phosphors is limited. Therefore, there is a demerit that the amount of phosphor used is increased as a whole.

  Recently, even in home lighting fixtures, it is possible to arrange a large number of light emitting diodes of the three primary colors of blue, green and red, or a light emitting diode packaged with the three primary colors, so that the emission intensity of each color can be adjusted independently. By doing so, products that are capable of not only dimming but also toning are sold. However, in this method, there are problems in that a large number of light emitting diodes are used and an intensity adjustment circuit for each color is complicated, and it is difficult to reduce the cost. In addition, since the wavelength distributions of the light emitting diodes of the three primary colors are local, even if they are combined, the non-uniformity of the wavelength distribution is still large and the region of pseudo white light is not emitted. Since the peak of blue light is stronger than the bodily sensation, eye fatigue due to blue light, which has been regarded as a problem in recent years, is also a problem.

  Therefore, an object of the present invention is to realize light-emitting diode illumination that is easy to manufacture with a simple structure as much as possible and has a uniform wavelength distribution.

  The present invention has been made in view of the above problems, and the first important item is to simplify the structure. The most effective way to simplify the structure is to avoid multilayering. However, at present, it is impossible to compensate for a plurality of wavelength band components that are insufficient for light-emitting diode illumination with a single type of phosphor. Therefore, it is necessary to arrange a plurality of phosphors in a single layer structure.

  As described above, when a single layer is formed by mixing a plurality of phosphors, a part of the light emitted from the phosphor located near the light emitting diode is absorbed by other phosphors before reaching the outside. As a result, the luminous efficiency decreases as a whole. Therefore, in the present invention, a plurality of phosphors are arranged as independent spots without being mixed and superimposed. However, since the uniformity of the light quantity cannot be realized when this spot becomes large, it is desirable to form each spot sufficiently small. Therefore, not only multiple types of phosphors are used, but also many fine spots are arranged even with the same type of phosphor. A body layer will be formed. With the recent development of printing technology, it is not so difficult to form such a fine pattern on a sheet.

  As described above, in the illumination method using the light emitting diode of the present invention, the phosphor layer is formed in a single unit, so that it is easy to manufacture and the light emitted from the phosphor is absorbed by other phosphors. Therefore, the luminous efficiency can be greatly increased. Since the total area ratio of each phosphor spot can be easily changed by applying printing technology, the shape of the wavelength spectrum of illumination can be freely changed, and illumination having various characteristics can be easily realized. Furthermore, since it is not necessary to combine the light emitting diode and the phosphor layer into a package, by separating these distances, the phosphor layer can be prevented from being altered by a large amount of heat generated in the light emitting diode, and the life can be extended. it can. Further, since the light emitting diode and the phosphor layer are separated, only the phosphor layer can be exchanged even when the phosphor layer is consumed, and resources can be used effectively.

    Hereinafter, an illumination method using the light emitting diode of the present invention will be described in detail with reference to the drawings.

  First, how the light emission of white light emitting diodes and sunlight (natural light) generally differs will be described. FIG. 2 shows wavelength distribution characteristics of a general white light emitting diode and sunlight. White light-emitting diodes use a blue light-emitting diode as a light source and excite yellow phosphors to emit light to synthesize blue light and yellow light to obtain pseudo-white light, and blue, green, and red light-emitting diodes of the three primary colors In general, the former with low manufacturing cost is generally used for lighting for daily life. As shown in FIG. 2, the wavelength distribution characteristics of this type of white light-emitting diode include a blue light-emitting band (peaking around a wavelength of 450 nm) that is an excitation light source and a phosphor light-emitting band (peaking around a wavelength of 580 nm). ) Are large, and there are few components between these and the red light emission band (wavelength of 630 nm or later). This is why it feels slightly paler than sunlight, where each wavelength band is relatively universal. In order to approximate the light emission of the white light emitting diode to sunlight, a method for compensating for these insufficient wavelength band components has been an issue.

  In order to solve this problem, the configuration of FIG. 1 is shown as an example of an illumination method using the light emitting diode of the present invention. In FIG. 1, a light emitting diode 102 is formed on a substrate 101. The light emitting diode 102 is mainly used as a light source, and a blue light emitting diode is used as an example. Furthermore, the support body 103 is arrange | positioned between the light emitting diode 102 and the illumination object. The support 103 fixes the phosphor 104 by a method such as coating, and also forms a case for a lighting fixture. Therefore, the support 103 is preferably a transparent body having no specific fluorescent component. However, when a desirable wavelength spectrum is obtained by combination with the fluorescent body 104, the support 103 may have a specific fluorescent component. Good. The phosphor 104 is excited by the light emitting diode 102 and emits a specific fluorescent component, and compensates for the insufficient portion of the light emitting component of the light emitting diode 102 to realize a wavelength spectrum desirable for use as pseudo white light or illumination. It is. In addition, in FIG. 1, although the fluorescent substance is arrange | positioned at the surface at the side of the illumination target of a support body, you may arrange | position at the surface at the side of a light emitting diode.

  If the phosphor 104 is formed of one layer or multiple layers and has uniform characteristics in each layer, there is no difference from the conventional white light emitting diode or the illumination method described in Patent Document 2. However, the illumination method using the light emitting diode according to the present invention is characterized in that although the phosphor 104 is a single layer, a plurality of phosphors having different fluorescence characteristics are distributed in the layer. The layer here is not necessarily formed continuously but may be formed from a plurality of independent spots. That is, a spot group formed on the same surface is also regarded as one layer.

From such characteristics, the invention according to claims 1 and 2 of the illumination method using the light emitting diode of the present invention can be described as follows.
(Claim 1)
An illumination method comprising a combination of a light emitting diode and a phosphor layer excited and emitted by the light emitting diode, wherein the phosphor layer is formed from a plurality of independent phosphor spots having different fluorescence characteristics. A lighting method using a light emitting diode.

(Claim 2)
The illumination method using a light emitting diode according to claim 1, wherein the plurality of independent phosphor spots having different fluorescence characteristics are arranged on the same surface.

  FIG. 3 shows an example of the phosphor layer of the illumination method using the light emitting diode of the present invention. In FIG. 3, a transparent support 302 is disposed on the light emitting surface side of the light emitting diode 301. The support 302 may be formed of a flexible material such as a film in addition to resin and glass. A plurality of phosphor spots are disposed on the support 302. The phosphor spots are arranged by a method such as coating, dripping, vapor deposition, etc. In particular, with the recent improvement in printing technology, it is possible to form even very fine spots. As an example of FIG. 3, the light emitting diode 301 emits blue light, and the phosphor spot 303 is excited by the blue light emitting diode and emits yellow light. Pseudo-white illumination can be realized by these combinations alone, but as described above, the wavelength component between the blue band and the yellow band and the wavelength component of the red band are insufficient, so that the phosphor spot 304 is excited by blue light and is green. A wavelength spectrum close to that of sunlight can be realized if the light-emitting material and the phosphor spot 305 are formed by being excited by blue light and emitting red light. As shown in FIG. 3, each phosphor spot does not necessarily have different characteristics, and a large number of spots made of the same phosphor may be scattered. In order to obtain as uniform illumination as possible as a whole, each phosphor spot should be as fine as possible. If the spot becomes finer, it is necessary to arrange as many spots made of the same phosphor.

Although it is preferable that the phosphor spot is as fine as possible, there is also a problem of manufacturing costs, and it is also important to determine the size of the phosphor spot that can be practically uniform. This is defined by the invention according to claim 3.
(Claim 3)
When the maximum value of the length of the line segment that can be taken inside the phosphor spot is the representative length, and the distance from the phosphor spot to the illumination object is the illumination distance, the value of the representative length / illumination distance is 0. The illumination method using the light emitting diode according to claim 1 or 2, wherein the illumination method is 1 or less.

  As for the shape of the phosphor spot, a circle, an ellipse, a rectangle, a line segment, and the like are listed, but not particularly limited thereto. In order for the luminescent component from each phosphor spot to be efficiently irradiated onto the object to be illuminated, it is preferable that the phosphor spots are arranged so that they do not overlap. If the body spots have a characteristic relationship that does not absorb, they may overlap.

In the illumination method using the light emitting diode of the present invention, it is also a great advantage that the distance between the light emitting diode and the phosphor layer can be increased. Physically, the wavelength characteristics are almost determined by the wavelength characteristics of the light-emitting diode that is the light source and the type and distribution ratio of the phosphor spots that form the phosphor layer, so the distance between the light-emitting diode and the phosphor layer depends on the wavelength characteristics. This is because it has almost no effect. If the distance between the light-emitting diode and the phosphor layer can be increased, the lifetime of the phosphor layer can be extended without being affected by the heat generated from the light-emitting diode, which is the greatest cause of deterioration of the phosphor layer. In a general white light emitting diode, since a blue light emitting diode and a yellow phosphor are integrated, deterioration of the phosphor due to heat generation of the light emitting diode determines the lifetime of the device. Therefore, if the light emitting diode and the phosphor layer can be separated and separated from each other, heat is not directly conducted and the life can be extended. Specifically, the distance separating them is preferably 1 mm or more, but not limited thereto. The invention according to claims 4 and 5 describes this advantage.
(Claim 4)
The illumination method using the light emitting diode according to claim 1, wherein the light emitting diode and the phosphor layer are separated.
(Claim 5)
The illumination method using the light emitting diode according to claim 4, wherein a distance between the light emitting diode and the phosphor layer is 1 mm or more.

Thus, the fact that the light-emitting diode and the phosphor layer can be separated from each other means that the phosphor layer can be formed according to the purpose by creating a sheet-like or tape-like one having the phosphor layer formed on the support. It is also possible to easily obtain different wavelength characteristics by exchanging. The invention according to claim 6 describes such a configuration.
(Claim 6)
The illumination method using a light emitting diode according to claim 1, wherein the phosphor layer is formed on a resin sheet, a film, or a tape.

  So far, the characteristics of the shape or position of the phosphor layer have been described. The main object of the present invention is to realize illumination having a uniform wavelength spectrum close to that of sunlight using a light emitting diode. Therefore, the combination of the wavelength characteristics of the light emitting diode and the phosphor layer is also a very important study subject. The following describes the invention from this point of view.

  First, as a precondition, in the illumination method using a light emitting diode of the present invention, a plurality of light emitting diodes are arranged on a substrate, and a phosphor layer excited and emitted by the light emitting diode is mainly formed from a plurality of phosphor spots. The configuration. This is because, as long as the main purpose is illumination, it is necessary to uniformly supply wavelength components according to the purpose within a certain range. If the plurality of light-emitting diodes and phosphor spots are all made of a single species (for example, a blue light-emitting diode and a yellow phosphor), it is not different from general white illumination. By changing these combinations in various ways, the characteristics of the illumination method using the light-emitting diode of the present invention can be obtained.

As described above, pseudo-white illumination can be obtained by combining a blue light emitting diode and a yellow phosphor, and by supplementing green and red components as wavelength components, it is possible to obtain illumination with a more uniform wavelength spectrum and close to sunlight. it can. In the present invention, as an example of a method for realizing this, a green light emitting diode and a red phosphor are used to supplement green and red components. The red phosphor may be any material that excites and emits light by either a blue light emitting diode or a green light emitting diode. This is the invention according to claims 7 and 8.
(Claim 7)
The illumination method using the light emitting diode according to claim 1, wherein a blue light emitting diode and a green light emitting diode are used as the light emitting diode.
(Claim 8)
The illumination method using a light emitting diode according to claim 7, wherein a yellow phosphor and a red phosphor are used as the phosphor layer.

  In addition, it is supplemented that the yellow phosphor and the red phosphor need to be arranged as phosphor spots at positions irradiated by light emitting diodes suitable as excitation light sources, respectively. The blue light emitting diode has a light emission peak in the wavelength range of 450 to 500 nm, and the green light emitting diode has a light emission peak in the wavelength range of 500 to 540 nm. The yellow phosphor contains 60% or more of emission energy in the wavelength range of 560 to 620 nm, and the red phosphor contains 70% or more of emission energy in the wavelength range of 630 to 770 nm. Examples of the material of the phosphor include silicate, YAG, TAG, BOS, sialon, and casoon.

In the visible light range, it is possible to obtain illumination close to natural light by adjusting the phosphor so that each wavelength component is as uniform as possible using a blue light emitting diode as a light source. In addition, a wavelength component shorter than blue, that is, a wavelength component from purple to ultraviolet having a wavelength of 450 nm or less cannot be obtained. The absence of these components is not a problem for everyday use, but for example, some clothing materials and dyes emit some blue fluorescence with ultraviolet light, which is different from the color under sunlight. There is a case. In applications where it is important to check the color under sunlight, it is necessary to supplement the wavelength components in the near-ultraviolet region, and what has been done in view of this is the invention according to claims 9 and 10. is there.
(Claim 9)
The illumination method using the light emitting diode according to claim 1, wherein a light emitting diode having a peak wavelength of 430 nm or less is used as at least a part of the light emitting diode.
(Claim 10)
10. The light emitting diode according to claim 9, wherein the phosphor layer is a phosphor that absorbs an excitation light component having a wavelength of 430 nm or less and exhibits a light emission characteristic having a peak in a region having a wavelength of 450 nm or more. Lighting method.

Furthermore, according to the illumination method using the light emitting diode of the present invention, various wavelength spectra can be realized by changing the ratio of each phosphor spot forming the phosphor layer. In the conventional method, in order to change the wavelength spectrum of illumination, the mixing ratio of phosphors is changed, or if a multilayer structure is used, the thickness of each layer must be changed, which is not easy. However, in the present invention, although a plurality of phosphors are used, it is not necessary to change the phosphors themselves. Changing the size and area ratio of each phosphor spot is not so difficult due to the application of printing technology, and illumination having various wavelength characteristics can be easily realized. This is the invention according to claims 11 and 12.
(Claim 11)
The emission wavelength distribution of the phosphor layer is changed by changing a size and / or abundance ratio of a plurality of phosphor spots forming the phosphor layer. An illumination method using a light emitting diode.
(Claim 12)
An illumination method using a light-emitting diode, wherein phosphor layers having at least two different emission wavelength distributions produced by the method according to claim 11 are incorporated in the same illuminator.

In addition, according to this method, by continuously changing the ratio and / or size of each phosphor spot, it is possible to easily realize illumination in which the emission color changes spatially continuously. In the method of adjusting the color by electrically controlling the light emitting diode, it is possible to continuously change the entire emitted color temporally, but it is extremely difficult to change spatially continuously. The present invention is useful, for example, when it is desired to quickly check the color.
(Claim 13)
The emission wavelength distribution of the phosphor layer is spatially continuously changed by continuously changing the size and / or the existence ratio of the plurality of phosphor spots forming the phosphor layer. An illumination method using the light emitting diode according to claim 11.

FIG. 4 shows a second embodiment of the illumination method using the light emitting diode of the present invention. In this embodiment, two types of phosphor spots, that is, a short wavelength phosphor spot 402 and a long wavelength phosphor spot 403 form a checkered pattern (check pattern) above the light emitting diode 401 (on the illumination object side). Are arranged to be. In this case, the light from the light-emitting diode does not directly pass through and always passes through one of the phosphor spots. However, since it is usually impossible to absorb all the light from the light-emitting diode, It becomes a synthetic spectrum of each light emission of the short wavelength phosphor and the long wavelength phosphor. Since a plurality of light emitting diodes are usually disposed as illumination, such a phosphor layer is disposed above each (illumination object side) as necessary. In some cases, such a phosphor layer may be disposed over the entire surface. Examples of combinations include the following configurations, which are described in the claims.
(Claim 14)
The phosphor spot forming the phosphor layer is composed of at least two kinds of phosphors and is arranged in a lattice pattern, The illumination using the light emitting diode according to claim 1, Method.
(Claim 15)
15. The illumination method using a light emitting diode according to claim 14, wherein the phosphor spots arranged in a lattice pattern are composed of two types of phosphors and are arranged so as to form a checkered pattern. .
(Claim 16)
The light emitting diode according to claim 14 or 15, wherein the light emitting diode has a characteristic with a peak wavelength of 480 nm or less, and the two kinds of phosphors emit yellow and green light respectively by the light emitting diode. Lighting method using
(Claim 17)
The light emitting device according to claim 14 or 15, wherein the light emitting diode has a characteristic with a peak wavelength of 480 nm or less, and the two kinds of phosphors emit yellow and orange light respectively by the light emitting diode. Lighting method using a diode.

In addition, it is possible to further improve the uniformity of wavelength distribution (color rendering) by increasing the types of phosphors. FIG. 5 shows an example in which the phosphor spot is composed of three types of phosphors. As in FIG. 4, phosphor spots are arranged in a lattice pattern above the light emitting diode 501 (on the illumination object side), but there are three types of phosphors: a short wavelength phosphor spot 502, a medium wavelength It becomes either the phosphor spot 503 or the long wavelength phosphor spot 504. In order to ensure uniformity, it is preferable to regularly arrange three types of phosphor spots as shown in FIG. Examples of combinations in this case include the following configurations, which are described in the claims.
(Claim 18)
The light emitting diode has a peak wavelength of 440 nm or more and 480 nm or less, and the phosphor spots arranged in the lattice pattern are composed of three kinds of phosphors, and the phosphors emit green, yellow, and red, respectively. The illumination method using the light emitting diode according to claim 14.
(Claim 19)
The light emitting diode has a characteristic with a peak wavelength of 440 nm or less, and the phosphor spots arranged in the lattice pattern are composed of three kinds of phosphors, and the phosphors emit blue, green and yellow light respectively. The illumination method using the light emitting diode according to claim 14.

  The lighting method using the light emitting diode of the present invention can be used for various applications such as indoor lighting, stage lighting, display lighting, plant growing light source, relaxation facility lighting, nursing facility lighting, nighttime outdoor lighting, and the like.

The figure which shows an example of the illumination method using the light emitting diode of this invention Wavelength distribution characteristics of general white light emitting diodes and sunlight The figure which shows an example of the fluorescent substance layer of the illumination method using the light emitting diode of this invention The figure which shows an example of the fluorescent substance layer of the illumination method using the light emitting diode of this invention The figure which shows an example of the fluorescent substance layer of the illumination method using the light emitting diode of this invention

DESCRIPTION OF SYMBOLS 101 Substrate 102 Light emitting diode 103 Support body 104 Phosphor layer 301 Light emitting diode 302 Support body 303 Phosphor spot 304 Phosphor spot 305 Phosphor spot 401 Light emitting diode 402 Short wavelength phosphor spot 403 Long wavelength phosphor spot 501 Light emitting diode 502 Short Wavelength phosphor spot 503 Medium wavelength phosphor spot 504 Long wavelength phosphor spot

Claims (19)

An illumination method comprising a combination of a light emitting diode and a phosphor layer excited and emitted by the light emitting diode, wherein the phosphor layer is formed from a plurality of independent phosphor spots having different fluorescence characteristics. A lighting method using a light emitting diode. The illumination method using a light emitting diode according to claim 1, wherein the plurality of independent phosphor spots having different fluorescence characteristics are arranged on the same surface. When the maximum value of the length of the line segment that can be taken inside the phosphor spot is the representative length, and the distance from the phosphor spot to the illumination object is the illumination distance, the value of the representative length / illumination distance is 0. The illumination method using the light emitting diode according to claim 1 or 2, wherein the illumination method is 1 or less. The illumination method using the light emitting diode according to claim 1, wherein the light emitting diode and the phosphor layer are separated. The illumination method using the light emitting diode according to claim 4, wherein a distance between the light emitting diode and the phosphor layer is 1 mm or more. The illumination method using a light emitting diode according to claim 1, wherein the phosphor layer is formed on a resin sheet, a film, or a tape. The illumination method using the light emitting diode according to claim 1, wherein a blue light emitting diode and a green light emitting diode are used as the light emitting diode. The illumination method using a light emitting diode according to claim 7, wherein a yellow phosphor and a red phosphor are used as the phosphor layer. The illumination method using the light emitting diode according to claim 1, wherein a light emitting diode having a peak wavelength of 430 nm or less is used as at least a part of the light emitting diode. 10. The light emitting diode according to claim 9, wherein the phosphor layer is a phosphor that absorbs an excitation light component having a wavelength of 430 nm or less and exhibits a light emission characteristic having a peak in a region having a wavelength of 450 nm or more. Lighting method. The emission wavelength distribution of the phosphor layer is changed by changing a size and / or abundance ratio of a plurality of phosphor spots forming the phosphor layer. An illumination method using a light emitting diode. An illumination method using a light-emitting diode, wherein phosphor layers having at least two different emission wavelength distributions produced by the method according to claim 11 are incorporated in the same illuminator. The emission wavelength distribution of the phosphor layer is spatially continuously changed by continuously changing the size and / or the existence ratio of the plurality of phosphor spots forming the phosphor layer. An illumination method using the light emitting diode according to claim 11. The phosphor spot forming the phosphor layer is composed of at least two kinds of phosphors and is arranged in a lattice pattern, The illumination using the light emitting diode according to claim 1, Method. 15. The illumination method using a light emitting diode according to claim 14, wherein the phosphor spots arranged in a lattice pattern are composed of two types of phosphors and are arranged so as to form a checkered pattern. . The light emitting diode according to claim 14 or 15, wherein the light emitting diode has a characteristic with a peak wavelength of 480 nm or less, and the two kinds of phosphors emit yellow and green light respectively by the light emitting diode. Lighting method using The light emitting device according to claim 14 or 15, wherein the light emitting diode has a characteristic with a peak wavelength of 480 nm or less, and the two kinds of phosphors emit yellow and orange light respectively by the light emitting diode. Lighting method using a diode. The light emitting diode has a peak wavelength of 440 nm or more and 480 nm or less, and the phosphor spots arranged in the lattice pattern are composed of three kinds of phosphors, and the phosphors emit green, yellow, and red, respectively. The illumination method using the light emitting diode according to claim 14. The light emitting diode has a characteristic with a peak wavelength of 440 nm or less, and the phosphor spots arranged in the lattice pattern are composed of three kinds of phosphors, and the phosphors emit blue, green and yellow light respectively. The illumination method using the light emitting diode according to claim 14.