JP2008311670A - White light emitting diode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a white light emitting diode having improved brightness and greatly improved similarity between a mixed color spectrum of phosphors and an actual sunlight spectrum. <P>SOLUTION: The white light emitting diode uses the phosphors which can be excited by a plurality of types of ultraviolet rays. Part of the phosphors forms a basic structure of the white light spectrum such as three types of red, green and blue light. The other part of the phosphors provides modification colored lights. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a white light-emitting diode, and more particularly to a white light-emitting diode manufactured by blending a plurality of types of fluorescent powder.

  White light is a mixed combined light of a plurality of facial colors, and a light beam identified as white light by the human eye includes a mixed light beam having at least two types of wavelengths. For example, if the human eye is stimulated by red, blue and green rays at the same time, or if it is stimulated by blue and yellow rays at the same time, it will all feel as white light, so based on such principles An LED light source that emits white light can be manufactured. There are five types of conventional white light LED manufacturing methods. The first type of method uses three LEDs made of AlInGaP, GaP, and GaN, and controls the current passing through each LED. , Emit light of green and blue colors. Since these three crystal granules are disposed in the same lamp, white light can be emitted by mixing the light beams emitted through the range. The second type uses two LEDs made of GaN and AlInGaP, and generates white light by emitting blue and yellow-green light by controlling the current passing through these LEDs. To do. At present, these two methods can reach a luminous efficiency of 20 lm / W. The third type is a white light source that was developed by Nichia Chemical Company in Japan in 1996 by combining an indium gallium nitride blue light emitting diode with a yttrium aluminum garnet fluorescent powder that emits yellow light. It is a method of manufacturing. The luminous efficiency of this method is slightly lower than the above-mentioned methods in the present case (which can reach 15 lm / W or more), but it does not require a single set of chips, so the manufacturing cost can be greatly reduced, Since the preparation technology of the fluorescent powder used together is already perfect, products have already been submitted. A fourth type of white light can be generated by a white light LED using ZnSe material, which was developed in January 1999 by two Sumitomo Electric Industries, Ltd. A CdZnSe thin film is formed on a chip substrate, and the thin film emits blue light after energization. A part of the blue light irradiates the substrate to emit yellow light. Finally, the blue light and yellow light are mutually transmitted. It complements and emits white light. Even in this method, since only one LED crystal granule is employed, the operating voltage is simply 2.7 V, which is lower than 3.5 V of InGaN LED, and white light can be obtained even without a fluorescent material. . It is an ultraviolet white light LED that is currently under development as a method for generating the fifth type of white light, that is, a method in the field of the present invention, and its principle is to excite three types of fluorescent powder by the ultraviolet LED. Thus, fluorescence is generated and white light is generated by color mixture. Conventional methods in the field are as follows.

1. A fluorescent powder having a composition of Y ₂ O ₃ : Eu, such as (Y _1.9 Eu _0.1 ) O _3, is synthesized. As the synthesis method, a solid reaction method or a chemical synthesis method such as a citrate gel method or A precipitation method or a microcolloid method can be employed.

2. SrAl ₂ O ₄ : Eu type fluorescent powder such as (Sr _0.96 Eu _0.04 ) Al ₂ O ₄ is synthesized and obtained as a synthesis method, such as a solid reaction method or a chemical synthesis method such as a citrate gel method. Or a coprecipitation method or a microcolloid method can be employed.

3. BaMgAl ₁₀ O ₁₇ : Eu type fluorescent powder such as (Ba _0.9 Eu _0.1 ) MgAl ₁₀ O ₁₇ is synthesized and obtained as a synthesis method, such as a solid reaction method or a chemical synthesis method such as a citrate gel method. Or a coprecipitation method or a microcolloid method can be employed.

  4). The three types of fluorescent powders are prepared in a predetermined proportion and the emission spectrum is detected using ultraviolet light having a wavelength of 396 nm as an excitation source, as shown in FIG. The emission spectrum data is converted into a chromaticity coordinate representative of the phosphor by a formula of a chromaticity coordinate diagram established by the International Commission on Illumination (Commission Internationale de 1 'Eclairage, CIE) in 1931. And it is marked in FIG.

  As can be seen from the above description, the method of manufacturing a white light LED by using an ultraviolet light emitting diode is to excite phosphors of the three primary colors of red, green and blue mainly by ultraviolet rays, and to prepare the phosphors in an appropriate proportion. Then, white light is obtained by mixing the colored light.

  However, in the case of white light generated by combining the spectrum configurations of the respective primary color phosphors, since the individual fluorescent powder is affected by having a predetermined spectrum configuration, the white light composed thereof Since the distribution and continuity of the wavelength of this spectrum do not reach true sunlight, it has disadvantages such as non-uniform color for white light and low saturation. The human eye can abbreviate these phenomena and only white light can be seen, but when it is detected by an optical detector with high precision, for example, by video or camera, its color rendering is still low. Considered, i.e., errors may occur when reducing the color of an object, so that a white light source produced by this type of scheme is only suitable for general lighting applications.

  The main object of the present invention is to propose a new white light emitting diode, and the white light emitting diode manufacturing method uses phosphors that can be excited by a plurality of types of ultraviolet light, and some of them are used. The phosphor forms the basic structure of the spectrum of three types of white light, such as red, green, and blue, and the other portion of the phosphor provides color light for modification, improves its brightness, The degree of similarity between the color mixture spectrum and the actual sunlight spectrum is greatly improved. Therefore, the present invention has an excellent point that white light-emitting diodes obtained by a technique for reinforcing and modifying a plurality of types of fluorescent powders can have high brightness and high color rendering properties.

  Another object of the present invention is to provide a light emitting diode capable of changing color emission. At present, as a method for obtaining a light-emitting diode capable of changing the light color, a plurality of single-color light-emitting diodes are combined with each other, the light emission order is controlled by an electric circuit, or a light-filtering piece or a hat cover having a different facial color. The light color is converted by. However, in the case of such a method, the manufacturing cost is high and it is not convenient, so it is necessary to develop a new feasible method. For example, a technique for reinforcing and modifying a plurality of kinds of fluorescent powders as described above is adopted, and all or some of the powder bodies have fluorescent or phosphorescent properties at the same time. The body obtains the effect of changing its light color over time, i.e., according to the method of the present invention, a light-emitting diode capable of changing color can be produced. Moreover, the light emitting diode which has a different color change order can be provided by changing the composition proportion of the powder pairs.

  Compared with the prior art, the method of the present invention is considerably simpler, lower in cost and rich in industrial utility.

  The features and technical contents of the present invention will be described in detail below with reference to the accompanying drawings, but these descriptions are merely a part of preferred embodiments of the present invention, and the scope of the present invention is narrowly defined. It is not defined.

  The present invention relates to a method of manufacturing a white light-emitting diode using a powder body having a plurality of types of fluorescent characteristics, applied to the light-emitting diode, and the white light-emitting diode. In this method, a light emitting diode capable of emitting ultraviolet light, an electron beam, plasma, or the like is used as an excitation light source, and three types of fluorescent powders are excited with each other to emit red light having a wavelength of 585 nm to 640 nm, green light having a wavelength of 500 nm to 570 nm, and 430 nm. Emits blue light of -490 nm. At the same time, in view of the fluorescence characteristics of these three wavelengths, such as emission intensity and color saturation, reinforcement or modification is performed by the fluorescence characteristics of one or more other fluorescent powders, and these four or more wavelengths are changed. The white light is generated after mixing the fluorescence provided. The white light obtained by the fluorescent reinforcement and modification technique of the present invention has an excellent point of high brightness and high color rendering than the conventional method of simply using phosphors of the three primary colors of red, green and blue.

  As one embodiment of the required fluorescent powder for synthesis and preparation of the white light emitting diode of the present invention (in one of the methods of the present invention, a method of showing the spectrum of white light obtained after modifying the spectrum structure) ) The following methods are mentioned.

1. A fluorescent powder having a composition of Y ₂ O ₃ : Eu, such as (Y _1.9 Eu _0.1 ) O _3, is synthesized. As the synthesis method, a solid reaction method or a chemical synthesis method such as a citrate gel method or A precipitation method or a microcolloid method can be employed.

2. SrAl ₂ O ₄ : Eu type fluorescent powder such as (Sr _0.96 Eu _0.04 ) Al ₂ O ₄ is synthesized and obtained as a synthesis method, such as a solid reaction method or a chemical synthesis method such as a citrate gel method. Or a coprecipitation method or a microcolloid method can be employed.

3. BaMgAl ₁₀ O ₁₇ : Eu type fluorescent powder such as (Ba _0.9 Eu _0.1 ) MgAl ₁₀ O ₁₇ is synthesized and obtained as a synthesis method, such as a solid reaction method or a chemical synthesis method such as a citrate gel method. Or a coprecipitation method or a microcolloid method can be employed.

4). The composition is Y ₃ Al ₅ O ₁₂ : Ce, Gd type fluorescent powder, for example, (Y _2.3 Ce _0.05 Gd _0.65 ) Al ₅ O ₁₂ is synthesized and acquired, and as its synthesis method, solid reaction method or chemical synthesis For example, a citrate gel method, a coprecipitation method, or a microcolloid method can be employed.

  5. The four types of fluorescent powders are prepared in a predetermined proportion and the emission spectrum is detected using ultraviolet light having a wavelength of 396 nm as an excitation source, as shown in FIG. The data of the emission spectrum is converted into chromaticity coordinates representing this mixed phosphor and is shown in FIG.

The present invention also relates to a method of manufacturing a kind of light-emitting diode capable of changing color, and a phosphor having phosphorescence characteristics is one or a plurality of phosphors of the plurality of phosphors, and the light colors are different from each other over time. Changes can be exhibited. SrAl ₂ O ₄ : Eu, M, CaAl ₂ O ₄ : Eu, M, Sr ₄ Al ₁₄ O ₂₅ : Eu, M, Y ₂ O ₂ S: Eu, M, ZnS: Cu, M, etc. Among them, transition metal, rare earth element, etc. can be adopted as M.

  Regarding one of the manufacturing examples of a discolorable light emitting diode manufactured by a powder having phosphorescent properties, the manufacturing steps are as follows.

1. A fluorescent powder having a composition of Y ₂ O ₃ : Eu, such as (Y _1.9 Eu _0.1 ) O _3, is synthesized. As the synthesis method, a solid reaction method or a chemical synthesis method such as a citrate gel method or A precipitation method or a microcolloid method can be employed.

2. The composition is SrAl ₂ O ₄ : Eu, Dy type fluorescent powder, for example, (Sr _0.94 Eu _0.04 Dy _0.02 ) Al ₂ O ₄ is synthesized and acquired, and as its synthesis method, solid reaction method or chemical synthesis method, For example, a citrate gel method, a coprecipitation method, a microcolloid method, or the like can be employed.

3. BaMgAl ₁₀ O ₁₇ : Eu type fluorescent powder such as (Ba _0.9 Eu _0.1 ) MgAl ₁₀ O ₁₇ is synthesized and obtained as a synthesis method, such as a solid reaction method or a chemical synthesis method such as a citrate gel method. Or a coprecipitation method or a microcolloid method can be employed.

4). The composition is Y ₃ Al ₅ O ₁₂ : Ce, Gd type fluorescent powder, for example, (Y _2.3 Ce _0.05 Gd _0.65 ) Al ₅ O ₁₂ is synthesized and acquired, and as its synthesis method, solid reaction method or chemical synthesis For example, a citrate gel method, a coprecipitation method, or a microcolloid method can be employed.

  5. The four types of fluorescent powders are prepared in a predetermined proportion, and the emission spectrum is detected using ultraviolet light having a wavelength of 396 nm as an excitation source. In addition, the UV excitation light source is removed, the emission spectrum is detected several times at predetermined time intervals, the data of these emission spectra are converted into the chromaticity coordinates of each time point, and more and more from point A The points go to and are marked in FIG.

  As shown in the table below, when comparing the white light spectrum of the embodiment of the present invention with the conventional method obtained by calculation, it can be seen that the color rendering properties and the color temperature of the present invention are much more preferable than the conventional one.

本発明の利点は、次の通りである。

The advantages of the present invention are as follows.

  1. As can be seen from FIG. 3, the method of the present invention (see the embodiment) and the conventional method can all obtain the effect that the chromaticity coordinates are located in the standard white light area, for example, (0.3130, 0.3245) and (0.3120, 0.3285) of the embodiment. Therefore, a white light emitting diode can be provided in the same manner as the white light diode of the present invention and the conventional method.

2. As shown in the table, in the case of the conventional method, white light composed of three primary colors of red, green, and blue is obtained by three kinds of fluorescent powders, the color rendering property is simply 85, and the color temperature is 6524K. (Absolute temperature). In the case of the embodiment of the present invention, the spectrum configuration is modified with Y ₃ Al ₅ O ₁₂ : Ce, Gd type yellow fluorescent powder, so that the color rendering property can be improved to 94 and the color temperature can be improved to 6550K. The main reason is that the distribution of the white light spectrum after modification of the spectral structure and the distribution of the true sunlight spectrum are close, thereby obtaining high color rendering properties. Therefore, in the case of the white light emitting diode of the present invention, Then, the color rendering is much better than the conventional method.

3. In the case of the white light emitting diode of the present invention, when the emission spectrum is modified, for example, the yellow light of the Y ₃ Al ₅ O ₁₂ : Ce, Gd type fluorescent powder or the BaMgAl ₁₀ O 17: Eu, Mn type fluorescent powder in the embodiment Of blue / green light (there is a relationship between the ratio of Eu / Mn in fluorescent powder and the relative intensity of the emitted blue / green wavelength, so they also have the functions of modifying and controlling their own color) ) Etc. are all close to the wavelength of green light, that is, areas that are sensitive to the human eye, which have an effect on increasing the intensity of the overall white light, so that the white of the present invention The light emitting efficiency of the light emitting diode is superior to the conventional method.

4). In the case of the white light emitting diode of the present invention, as shown in FIG. 4, (Sr _0.94 Eu _0.04 Dy _0.02 ) Al ₂ O ₄ in the mixed fluorescent powder has a green phosphorescence characteristic. When the excitation light source is removed, the light color of the powder body gradually changes from white to green, and a predetermined time can be maintained. Similarly, if a powder body having two or more types of phosphorescence characteristics is used, the conversion of the light color generated becomes diverse. Therefore, when mixing a plurality of types of powder bodies so as to have a predetermined proportion according to the method of the present invention, and when using an ultraviolet light emitting diode of a predetermined wavelength (in this example, 396 nm) as an excitation light source, And when appropriately packaged, when a predetermined current is passed, a light emitting diode capable of converting the light color at any time can be obtained if excitation is stopped after the powder bodies to be mixed are irradiated with ultraviolet rays.

  The above-described embodiments of the present invention are merely specific examples of the present invention, and the gist of the present invention is not limited to them in a narrow sense, and any of the three main wavelengths is 585 nm to 640 nm at the same time. A phosphor capable of emitting three primary colors, such as red light, 500 nm-570 nm green light, and 430 nm-490 nm blue light, are combined with one or more other fluorescent powders to enhance and modify the white light spectrum. All changes and modifications carried out for the purpose of obtaining an excellent white light emitting diode capable of obtaining high brightness and high color rendering by means capable of being delivered should be delivered within the scope of the patent claim of the present invention. The present invention also relates to a method of manufacturing a light-emitting diode capable of changing color, and a phosphor having phosphorescent characteristics is used as one or more components of the plurality of types of phosphors, so that the light color varies with time. A color change can be produced.

The white light spectrum in the case of emitting fluorescence of red, green, and blue with three kinds of fluorescent powders such as conventional Y ₂ O ₃ : Eu, SrAl ₂ O ₄ : Eu, BaMgAl ₁₀ O ₁₇ : Eu, respectively. It is explanatory drawing shown. The three kinds of fluorescent powders such as Y ₂ O ₃ : Eu, SrAl ₂ O ₄ : Eu, BaMgAl ₁₀ O ₁₇ : Eu of the present invention emit red, green, and blue color fluorescence, respectively, and Y ₃ Al _{5 O 12: Ce,} is an explanatory diagram showing the spectrum of the white light emitted by combining yellow fluorescence emission of Gd phosphor. It is explanatory drawing which shows the chromaticity coordinate A and B of the mixed fluorescent powder which could be calculated based on the vector which FIG. 1 and FIG. Simultaneously with the present invention, Y ₂ O ₃ : Eu, SrAl ₂ O ₄ : Eu, Dy, BaMgAl ₁₀ O ₁₇ : Eu, Y ₃ Al ₅ O ₁₂ : Ce, Gd phosphor is mixed to emit white light first. It is a change figure which shows the condition where the light color at the time of making it a point and removing an ultraviolet excitation light source changes with progress of time.

Claims (3)

A white light emitting diode provided by mixing red light, green light and blue light emitted by exciting red phosphor, green phosphor and blue phosphor with ultraviolet light, respectively,
Including at least other phosphors having phosphorescent properties,
The other phosphors emit light of different colors over time.
White light emitting diode. The other phosphor is excited by ultraviolet light or visible light.
The white light emitting diode according to claim 1. The other phosphors include SrAl ₂ O ₄ : Eu, M, CaAl ₂ O ₄ : Eu, M, Sr ₄ Al ₁₄ O ₂₅ : Eu, M, Y ₂ O ₂ S: Eu, M, Selected from the group comprising ZnS: Cu, M, wherein M is a transition metal or a rare earth element,
The white light emitting diode according to claim 1.

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