JP2006233051A - Red light-emitting phosphor and light-emitting module using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a red light-emitting phosphor having a luminous efficiency higher than that of the conventional and to provide a high-luminance light-emitting module using the same. <P>SOLUTION: The red light-emitting phosphor is represented by the formula: (M<SB>1-x</SB>, Eu<SB>x</SB>)P<SB>3</SB>O<SB>9</SB>(wherein M is a rare earth metal element; and 0≤x<1), desirably has an excitation peak wavelength of 350 to 420 nm, more desirably 385 to 405 nm. It can constitute a high-luminance light-emitting module when combined with a semiconductor light-emitting element of an emission peak wavelength of 350 to 420 nm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a red light emitting phosphor and a light emitting module using the red light emitting phosphor, and more particularly, to a red light emitting phosphor having higher light emission efficiency than the conventional one and a high luminance light emitting module using the red light emitting phosphor.

In light of environmental issues and power savings, light source diodes (LEDs) and semiconductor lasers (LDs) that do not use mercury are combined with phosphors as excitation light sources, and light sources at that time are used as light sources. Has been.
For example, Patent Document 1 exhibits white light emission as a whole by additive mixing with yellow light emission from a Ce-activated rare earth aluminate phosphor that emits light by absorbing part of blue light emission. A light emitting diode is disclosed. However, this type of combination has a problem in color rendering properties because the emission color of white light finally obtained is limited, and color reproducibility under illumination of this light source is not reproduced in a preferable color.
In recent years, in order to solve such problems, as a method for compensating for the disadvantages of white synthesis by adding two colors, ultraviolet or short-wavelength visible light is used as primary light (excitation light) from a semiconductor light emitting device, and green, blue, A light emitting module by mixing phosphors of three red components has been introduced (for example, see Patent Document 2). Here, BaMgAl ₁₀ O ₁₇ : Eu ²⁺ , (Sr, Ca, Ba) ₅ (PO ₄ ) ₃ Cl: Eu ^2+, etc. are used as the blue light-emitting phosphor, and Ca ₈ Mg (SiO ₄ ) ₄ is used as the green light-emitting phosphor. Cl: Eu ²⁺ , Mn ²⁺ , BaMgAl ₁₀ O ₁₇ : Eu ²⁺ , Mn ^2+, etc. As red-emitting phosphors, Y ₂ O ₂ S: Eu ²⁺ (YOS: Eu), Y ₂ O ₃ : Eu, Bi, etc. are mentioned.

  However, among phosphors that emit red, green, and blue colors, red phosphors have lower luminous efficiency than phosphors that emit green and blue colors, so that a desired white color (for example, chromaticity x / In order to obtain y = 0.36 / 0.365), this red light emitting phosphor must be mixed in a larger proportion than the phosphors emitting green and blue colors, for example, the mixing ratio must be close to 90%. did not become. For this reason, the compounding ratio of the green and blue light emitting phosphors having good luminous efficiency is lowered, and a light emitting module that emits white with high luminance cannot be obtained.

Japanese Patent No. 2927279 JP 2004-127988 A

  Accordingly, an object of the present invention is to solve the above-mentioned problems, and to provide a red light-emitting phosphor having a higher luminous efficiency than conventional ones and a high-luminance light-emitting module using the same.

  As a result of intensive studies, the present inventors have achieved the above object by adopting the following configuration, and have achieved the present invention.

(1) A red light emitting phosphor represented by the following general formula.

(M _1-x , Eu _x ) P ₃ O ₉

(Wherein M is a rare earth element and 0 ≦ x <1)

(2) The red light-emitting phosphor according to (1), wherein the excitation peak wavelength is 350 to 420 nm.
(3) The red light emitting phosphor according to (2), wherein the excitation peak wavelength is 385 to 405 nm.

(4) A light emitting module comprising at least a semiconductor light emitting element having an emission peak wavelength of 350 to 420 nm and any one of the red light emitting phosphors (1) to (3).
(5) The light emitting module according to (4), wherein a phosphor that emits another color is used as a constituent.
(6) The light emitting module according to (5), wherein the phosphors emitting other colors are at least a green light emitting phosphor and a blue light emitting phosphor and emit white light.

FIG. 6 shows Y ₂ O ₂ S: Eu ²⁺ (YOS: Eu), which is an example of a conventional red light emitting phosphor, and BaMgAl ₁₀ O _17, which is an example of a phosphor emitting green and blue colors: Excitation spectra of Eu ²⁺ , Mn ²⁺ (BAM: Eu, Mn) and BaMgAl ₁₀ O ₁₇ : Eu ²⁺ (BAM: Eu) are shown. The red-emitting phosphor YOS: Eu is green / blue. It can be seen that the excitation efficiency with near ultraviolet light of 370 nm or more is lower than phosphors emitting each color.

As a result, the present inventors diligently studied, and as a result, EuP ₃ O _9, which is an example of the red light emitting phosphor of the present invention, has a maximum conversion efficiency in the excitation light region of 385 to 405 nm as shown in FIG. In addition, as shown in FIG. 5, when 395 nm is the primary light, the visual sensitivity is higher than that of the comparative example, that is, light is emitted on the shorter wavelength side (590 to 620 nm) than the emission peak of 628 nm of the comparative example. The inventors have found that the luminance is high and have come to make the present invention.

  Since the red light emitting phosphor of the present invention has higher luminous efficiency than the conventional one, for example, even when a light emitting module is formed by combining an ultraviolet light emitting semiconductor element and other phosphors as necessary, the light emitting module The blending ratio (amount) can be reduced. As a result, the blending ratio (amount) of other phosphors having good light emission efficiency can be increased. As a result, high-luminance light can be emitted, and color change due to blending errors can be reduced.

  The red light emitting phosphor of the present invention is represented by the following general formula.

(M _1-x , Eu _x ) P ₃ O ₉

(Wherein M is a rare earth element and 0 ≦ x <1)

Such a red light-emitting phosphor represented by the above general formula has an excitation peak wavelength of 350 to 420 nm, and among them, the excitation peak wavelength is preferably 385 to 405 nm. Moreover, the thing whose emission peak wavelength is 590-630 nm is preferable.
In the red light-emitting phosphor represented by the above general formula, M is a rare earth element, and x is 0 or more and less than 1.
Specifically, EuP ₃ O ₉ is preferable.

The red light-emitting phosphor of the present invention can be combined with an ultraviolet light-emitting semiconductor element and, if necessary, another phosphor to form a light-emitting module. For example, a white light emitting module can be obtained by combining an ultraviolet light emitting semiconductor element and green / blue light emitting phosphors.
In this case, the white light emitting module basically uses a green light emitting phosphor and a blue light emitting phosphor in addition to the red light emitting phosphor of the present invention, but in order to obtain white having a desired chromaticity. It is also possible to use a phosphor that emits light other than red, green, and blue. When using a phosphor that emits light other than red, green, and blue, the mixing ratio of the red light-emitting phosphor of the present invention is preferably 75% by mass or less based on the total phosphor. .

On the other hand, when only the red light emitting phosphor (R), the green light emitting phosphor (G), and the blue light emitting phosphor (B) of the present invention are used as the phosphor, the blending ratio (mass) thereof is (R ) 35-75: (G) 15-50: (B) 2-30, more preferably (R) 45-74: (G) 20-45: (B) 5-15. .
Although it does not specifically limit as fluorescent substance other than the red light emission fluorescent substance of this invention, The conventionally well-known and publicly known fluorescent substance can also be used suitably.

In addition, a publicly known and used red light-emitting phosphor can be used as appropriate in combination with the red light-emitting phosphor of the present invention.
Conventionally known and used phosphors include those described in the background art section of this specification.
The phosphor other than the red light-emitting phosphor that can be used in combination with the present invention, which is essential for the light-emitting module, and the conventionally known and used red light-emitting phosphor are preferably UV-resistant.

The semiconductor light-emitting device used in the light-emitting module using the red light-emitting phosphor of the present invention is not particularly limited as long as the emission peak wavelength is 350 to 420 nm. InGaN / GaN generally used as a semiconductor light-emitting device that emits ultraviolet light. The system type is preferred. Specifically, those described in JP-A-2002-17100 can be suitably used.
In an InGaN / GaN-based semiconductor light emitting device, the emission peak wavelength becomes longer as the In amount increases, and the emission peak wavelength becomes shorter as the In amount decreases. Therefore, in order to apply the InGaN / GaN-based semiconductor light emitting device to the light emitting module, the amount of In is adjusted as appropriate so that the emission peak wavelength becomes 350 to 420 nm.

A light emitting module using the red light emitting phosphor of the present invention is composed of the above semiconductor light emitting element and the phosphor containing the red light emitting fluorescent light of the present invention. And a structure in which the phosphor layer is provided.
In that case, the phosphor layer provided on the semiconductor light emitting element may be a single layer or a plurality of layers of at least one phosphor, or a plurality of phosphors may be arranged in a single layer. You may mix and arrange in. As a form in which the phosphor layer is provided on the semiconductor light emitting element, a form in which the phosphor is mixed with a coating member that covers the surface of the semiconductor light emitting element, a form in which the phosphor is mixed with the mold member, or a covering that covers the mold member And a mode in which a translucent plate in which the phosphor is mixed is disposed in front of the light emitting side of the semiconductor light emitting element lamp.

  In addition, at least one of the aforementioned phosphors may be added to the mold member on the semiconductor light emitting device. Furthermore, you may provide the fluorescent substance layer which consists of at least 1 type or more of the above-mentioned fluorescent substance on the outer side of a light emitting module. As a form provided on the outside of the light emitting module, a form in which the phosphor is applied in layers on the outer surface of the mold member of the light emitting module, or a molded body in which the phosphor is dispersed in rubber, resin, elastomer or the like (for example, cap shape) The form which coats this to a semiconductor light emitting element, or the form which processes the above-mentioned fabrication object in the shape of a plate, and arranges this in front of a semiconductor light emitting element, etc. are mentioned.

An example of a specific form of a light emitting module using the red light emitting phosphor of the present invention is shown in FIG. In the light emitting module shown in FIG. 2, one chip is a short wavelength visible light LED chip having an InGaN active layer and a center wavelength of around 395 nm. This short wavelength visible light LED chip 1 is connected to a lead frame 2 via an adhesive layer. It is fixed to. The short wavelength visible light LED chip 1 and the lead frame 2 are electrically connected by a gold wire 3. The short wavelength visible light LED chip 1 is covered with a phosphor paste 4 in which a phosphor powder is kneaded with a binder resin. Examples of the binder resin of the phosphor paste 4 include silicone resin, epoxy resin, urethane resin, norbornene resin, fluorine resin, metal alkoxide, polysilazane, and acrylic resin. In addition, the light emitting module has a sealing material 5 that covers the periphery of the phosphor paste 4. Examples of the sealing material 5 include materials that are transparent to visible light, such as silicone resin, epoxy resin, urethane resin, norbornene resin, fluorine resin, acrylic resin, and low-melting glass.
In addition, the form for light emitting modules is not limited to this light emitting module structure, For example, there exist various forms, such as coating the light emission surface of the short wavelength visible light LED chip 1 as a fluorescent substance layer.

  The white light emitting module using the red light emitting phosphor of the present invention has a predetermined whiteness, and is preferably in accordance with the following numerical prescription range which is the white prescription of the vehicle lamp of JIS D 5500. In the chromaticity diagram, this corresponds to the shaded portion in FIG.

Yellow direction x ≦ 0.50
Blue direction x ≧ 0.31
Green direction y ≦ 0.44 and y ≦ 0.15 + 0.64x
Purple direction y ≧ 0.05 + 0.75x and y ≧ 0.382

  A more preferable whiteness defining range is as follows, and if shown in the chromaticity diagram, it corresponds to the shaded portion of FIG.

  0.310 ≦ x ≦ 0.405 and blackbody radiation locus ≦ y ≦ 0.15 + 0.64x

The present invention will be described more specifically with reference to the following examples. However, the scope of the present invention is not limited to these examples.
[Example 1]
Preparation of EuP ₃ O _{9 As} a phosphor constituent raw material, 7.926 g of (NH ₄ ) H ₂ PO ₄ powder and 3.519 g of Eu ₂ O ₃ powder are precisely weighed and carefully mixed uniformly in an alumina mortar. . This raw material mixture was placed in an alumina crucible and fired at 600 ° C. for 6 hours in the atmosphere. The obtained baked product was finely pulverized, washed thoroughly with warm pure water, filtered and dried to prepare the target phosphor.

As shown in FIG. 1, the red phosphor obtained in Example 1 has a shorter wavelength visible light than the conventional red phosphor Y ₂ O ₂ S: Eu ³⁺ (comparative example). And has a strong excitation spectrum distribution around 395 nm, and emits light with high efficiency when the wavelength in this region is the primary light.
Next, FIG. 5 shows an emission spectrum distribution when 395 nm is the primary light. As shown in FIG. 5, light is emitted in red, which has higher visibility than the comparative example, that is, red on the shorter wavelength side (590 to 620 nm) than the emission peak 628 nm of the comparative example. As a result, Table 1 shows the result of comparing the emission luminance when 395 nm is the primary light with the comparative example. The phosphor of Example 1 has a luminance about 5 times that of the comparative example. From this, it can be seen that the phosphor of Example 1 can efficiently convert the light emitted from the short wavelength visible light LED chip into red light.

Production of Light Emitting Module As a semiconductor light emitting device, the InGaN / GaN LED chip having an emission wavelength of 395 nm and an external quantum efficiency of 18% is used as a red light emitting phosphor. BaMgAl ₁₀ O ₁₇ : Eu ²⁺ (hereinafter referred to as BAM: Eu), BaMgAl ₁₀ O ₁₇ : Eu ²⁺ , Mn ²⁺ (BAM: Eu, Mn) were used as the respective color light emitting phosphors.
In order to examine the light emission characteristics of the region surrounded by AGDC in FIG. 4 which is a desired chromaticity range for vehicle lighting using the LED chip and each color light emitting phosphor, the F coordinate (x , Y = 0.36, 0.365).

  Specifically, a ball mill was mixed with the above-described light emitting phosphors (red, green, and blue) at a blending ratio shown in Table 2 to prepare a mixed phosphor. The mixed phosphor and silicone resin (JCR-6125 manufactured by Toray Dow Corning Silicone Co., Ltd.) were mixed at 1: 1 to prepare a phosphor paste. The phosphor paste was potted to cover the LED chip fixed in a lead frame shaped like a cup and cured at 150 ° C. for 1 hour to immobilize the mixed phosphor on the LED chip.

Light Emitting of Light-Emitting Module The produced light-emitting module was made to emit light by energizing the LED chip with a driving current of 20 mA and a driving voltage of 3.5 V. The average color rendering properties (Ra) of each light emitting module are shown in Table 2 below.

  Table 3 below shows the light emission efficiency and the light emission luminance of the light emitting module that emits each light of whiteness F (x, y = 0.360, 0.365) in Example 1 and Comparative Example.

  From the above results, the light emitting module of Example 1 was able to reduce the amount of red light emitting phosphor and increase the luminance as compared with the light emitting module of the comparative example. Moreover, the white light emission of the light emitting module of Example 1 was desirable with the color rendering property Ra of 60 or more.

  The red light emitting phosphor of the present invention can constitute a light emitting module by combining, for example, an ultraviolet light emitting semiconductor element and another phosphor, and the light emitting module can be applied to, for example, a vehicle lamp. Can be expected.

Example 1 of the red-emitting phosphor EuP ₃ O ₉ and conventional red light emitting phosphor Y ₂ O ₂ S: is a diagram showing the excitation spectrum of Eu ^2+. It is a figure which shows one example of the form of the light emitting module using the red light emission fluorescent substance of this invention. It is a chromaticity diagram which shows the preferable range of the whiteness of the light which the white light emitting module using the red light emission fluorescent substance of this invention light-emits. It is a chromaticity diagram which shows the more preferable range of the whiteness of the light which the white light emitting module using the red light emission fluorescent substance of this invention light-emits. When the primary light 395 nm, is a diagram showing an emission spectrum distribution of EuP ₃ O ₉ of Example 1. It is a figure which shows the luminous efficiency of the fluorescent substance (BAM: Eu and BAM: Eu, Mn respectively) which light-emit the conventional red light emission fluorescent substance YOS: Eu and each color of blue and green.

Explanation of symbols

1 LED chip 2 Lead frame 3 Metal wire 4 Phosphor paste 5 Sealing material

Claims (6)

A red light-emitting phosphor represented by the following general formula.
(M _1-x , Eu _x ) P ₃ O ₉
(Wherein M is a rare earth element and 0 ≦ x <1)   The red light-emitting phosphor according to claim 1, wherein an excitation peak wavelength is 350 to 420 nm.   The red light emitting phosphor according to claim 2, wherein the excitation peak wavelength is 385 to 405 nm.   A light emitting module comprising at least a semiconductor light emitting element having an emission peak wavelength of 350 to 420 nm and the red light emitting phosphor according to claim 1.   5. The light emitting module according to claim 4, wherein a phosphor emitting another color is used as a constituent. 6. The light emitting module according to claim 5, wherein the phosphors emitting other colors are at least a green light emitting phosphor and a blue light emitting phosphor and emit white light.

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