JP2005167138A - White light emitting element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a white light source which can generate white light having a sufficient luminous intensity of a red component and having a high brightness and an excellent color rendering, be suitably used in illumination, backlight, indicator, electrical decoration, etc. of a liquid crystal display device, and have a good luminous efficiency. <P>SOLUTION: A white light emitting element comprises a blue light emitting diode chip, yellow light emitting phosphor for emitting yellow fluorescence when stimulated with blue light, and a red light emitting phosphor for emitting red fluorescence when stimulated with blue light. A lithium borate based phosphor containing europium as an activator is used as the red light emitting phosphor. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a white light emitting device.

Recently, white light-emitting elements have attracted attention and have been put to practical use as new white light sources and white light-emitting elements that can be used for backlights, various indicators, and illumination of liquid crystal display devices. For example, a white light-emitting element described in Patent Document 1 includes a phosphor (Y, Gd) ₃ (Al, Ga) ₅ O ₁₂ in which a YAG-based oxide matrix lattice known by the composition formula is doped with Ce ( A structure in which a YAG: Ce phosphor) is dispersed in a sealing resin surrounding a blue light emitting diode chip (hereinafter referred to as a blue light emitting diode) using a nitride compound semiconductor is employed. However, the white light emitting device having the above structure has a problem that the light emission intensity in the red region (647 nm to 700 nm) is insufficient, color reproducibility is poor, and color rendering is low.

Patent Document 2 discloses a white light emitting element that compensates for the shortage of the red component of white output light and solves the above problems. The white light-emitting element described in Patent Document 2 is obtained by dispersing and encapsulating a yellow light-emitting phosphor YAG: Ce and a red light-emitting phosphor in a sealing resin surrounding a blue light-emitting diode. The color rendering property is improved by increasing the red component to compensate for the shortage of red in the output light. The white light emitting element of Patent Document 2 uses a Y ₂ O ₂ S: Eu phosphor or the like as a red phosphor.

Japanese Patent No. 2927279 JP 2002-299691 A

  As described above, the white light emitting element of Patent Document 1 obtains white by combining a blue light emitting diode and a YAG: Ce phosphor that emits yellow light when excited by blue light emission. : The combination of only Ce phosphors has a problem that the light emission intensity of the red component is weak and the color rendering property is poor when the white light emitting element is applied to illumination or the like.

Further, the white light emitting element of Patent Document 2 that has solved the disadvantages of Patent Document 1 does not have sufficient red emission intensity of the red phosphor Y ₂ O ₂ S: Eu mixed with the YAG: Ce phosphor. For this reason, in order to make the color rendering property improving effect sufficient, it is necessary to increase the red light emission intensity by increasing the amount of mixture of the red light emitting phosphor Y ₂ O ₂ S: Eu excited and emitted by blue light. is there. However, increasing the mixing amount of the Y ₂ O ₂ S: Eu phosphor in the red-emitting phosphor decreases the mixing ratio of the YAG: Ce phosphor, resulting in a decrease in the brightness of white light. There's a problem.

  The present invention solves the above problems, has a red component with sufficient light emission intensity, has high luminance, and excellent color rendering properties, and backlights, indicators, illuminations, etc. of lighting and liquid crystal display devices An object of the present invention is to provide an efficient white light-emitting element suitable for the light source.

  The white light emitting device of the present invention is excited by a blue light emitting diode, a yellow light emitting phosphor that emits yellowish fluorescent light when excited by blue light from the blue light emitting diode, and blue light from the blue light emitting diode. A red light-emitting phosphor that emits red fluorescence, and a europium-activated lithium borate-based phosphor is used as the red light-emitting phosphor.

Europium-activated lithium borate phosphor is a LiLa _2-x Eu _x BO ₅ phosphor (provided that 0.01 ≦ x ≦ 1.0) in consideration of excitation intensity, fluorescent hue, etc. Or a Li _2−x Eu _x B ₂ O ₄ phosphor (provided that 0.01 ≦ x ≦ 1.0).

  As a yellow light-emitting phosphor that absorbs blue light and emits yellow light, for example, a perylene-based phosphor can be used as an organic phosphor. As the inorganic phosphor, an aluminate phosphor, a phosphate phosphor, a silicate phosphor, or the like can be used. Among these, perylene-based phosphors and YAG-based phosphors are preferable because they can be used for a long time. Moreover, as an activator, elements, such as Ce, Eu, Mn, Gd, Sm, Tb, Sn, Cr, Sb, can be used, for example. Of these, Ce is preferable. As a combination of the phosphor and the activator, a YAG: Ce phosphor of a combination of YAG and Ce is preferable.

  The yellow light-emitting phosphor and the red light-emitting phosphor may be used by mixing them, or the yellow light-emitting phosphor and the red light-emitting phosphor may be spatially separated. Specifically, a configuration in which a mold resin containing a yellow light-emitting phosphor and a mold resin containing a red light-emitting phosphor are alternately laminated in layers covering a blue light-emitting diode chip, or two blue light-emitting diodes Prepare a chip, arrange a red light emitting phosphor on one blue light emitting diode chip side, excite and emit the red light emitting phosphor by light emission of one blue light emitting diode chip, and on the other blue light emitting diode chip side There is a configuration in which a yellow light-emitting phosphor is arranged and the yellow light-emitting phosphor is excited and emitted by light emission of the other blue light-emitting diode chip.

  The white light emitting device of the present invention may have a configuration in which a fluorescent layer is provided on the uppermost layer of a blue light emitting diode chip having a semiconductor multilayer structure including a light emitting region. The phosphor layer may be any phosphor layer in which the phosphor is formed into a film, or a layer in which a medium such as a resin containing the phosphor is formed in a film (phosphor-containing layer). Form may be sufficient. Furthermore, the phosphor layer may use a passivation film in which a phosphor is dispersed as the passivation film and phosphor layer.

  The white light emitting device of the present invention is a lithium borate phosphor that efficiently excites and emits light in blue light in the emission wavelength region of a blue light emitting diode, to a red light emitting phosphor used in combination with a yellow light emitting phosphor. Used. Therefore, red light emission intensity is improved, and white light having a red component with sufficient light emission intensity, high luminance, and excellent color rendering is obtained.

The white light emitting device of the present invention includes a blue light emitting diode, a yellow light emitting phosphor that emits yellow fluorescent light when excited by blue light from the blue light emitting diode, and a red light that is excited by blue light from the blue light emitting diode. And a red light-emitting phosphor that emits the fluorescent light. A lithium borate phosphor using europium as an activator was used as the red light emitting phosphor. Specifically, a LiLa _2−x Eu _x BO ₅ phosphor (provided that 0.01 ≦ x ≦ 1.0) or a Li _2−x Eu _x B ₂ O ₄ phosphor (provided that the ratio is 0. 01 ≦ x ≦ 1.0) was used.

  Hereinafter, specific examples of the configuration will be described in detail with reference to the drawings.

FIG. 1 shows a cross-sectional view of the white light-emitting element of Example 1 (hatching indicating the cross section is not shown, and hatching is also omitted in Example 2 and later). In the white light emitting device of the first embodiment, the blue light emitting diode 1 is embedded in a transparent resin 4 such as epoxy formed on a transparent substrate 3 made of glass, quartz glass or the like. The transparent resin 4 includes a phosphor blended with a powdery YAG: Ce phosphor 2a and a red light emitting phosphor LiLa _2-x Eu _x BO ₅ (0.01 ≦ x ≦ 1.0). Is distributed. Specifically, LiLa _1.8 Eu _0.2 BO ₅ phosphor 2b was used as the red light emitting phosphor. The surface 4a of the transparent resin 4 is mirror-processed (for example, an Al film coating) so as to act as a mirror, and the light emitted from the blue light-emitting diode 1 is reflected in the direction of the transparent substrate 3 so that the transparent substrate 3 efficiently It has a structure that can output light output.

In the white light emitting device, a part of the blue light emitted from the blue light emitting diode 1 is absorbed by the phosphor YAG: Ce, LiLa _1.8 Eu _0.2 BO ₅ and converted into yellow light and red light. The yellow light and red light from the phosphor and the blue light from the blue light emitting diode 1 are mixed and emitted from the transparent substrate 3 as white light.

The amount of the red light emitting phosphor LiLa _1.8 Eu _0.2 BO ₅ blended with the YAG: Ce phosphor 2a may be adjusted according to the use of the white light emitting element. If you need reddish white light, use _more LiLa _1.8 Eu _0.2 BO ₅ phosphor 2b, and if you need pale white light, LiLa _1.8 Eu _0.2 BO What is necessary is just to prepare ₅ phosphor 2b slightly. In this example, the amount of the red light emitting phosphor LiLa _1.8 Eu _0.2 BO ₅ was adjusted so as to be closest to natural white light.

FIG. 2 shows the effect of using LiLa _1.8 Eu _0.2 BO ₅ which is a lithium borate phosphor as a red light emitting phosphor used in a white light emitting device.

FIG. 2 shows an excitation spectrum (curve 31) of a lithium borate phosphor LiLa _1.8 Eu _0.2 BO ₅ which is a red light emitting phosphor used in the white light emitting device in the example, red was used in the light-emitting element emitting phosphor Y _{2 O 2 S:} is a diagram showing the excitation spectrum (curve 33) of Eu. In the figure, the horizontal axis represents wavelength and the vertical axis represents excitation intensity. The excitation spectrum indicates the excitation wavelength dependency with respect to the wavelength at which the maximum emission intensity is obtained. As is clear from the figure, the red light-emitting phosphor of the example and the conventional red light-emitting phosphor have the maximum excitation intensity in the vicinity of 460 nm to 470 nm, which is the emission wavelength of the blue light-emitting diode. It can be seen that the red light-emitting phosphor used has an excitation intensity approximately twice that of the conventional red light-emitting phosphor. From this, the red light-emitting phosphor used in the examples absorbs blue light in the vicinity of a wavelength of 460 nm to 470 nm more efficiently than the conventional red light-emitting phosphor Y ₂ O ₂ S: Eu. I understand that As a result, the white light emitting device of this example using the LiLa _1.8 Eu _0.2 BO ₅ phosphor, which is a lithium borate phosphor, as the red light emitting phosphor is more than the conventional white light emitting device. It can be seen that the red component is increased and the color rendering property is excellent.

The yellow phosphor YAG: Ce and the red light-emitting phosphor LiLa _2-x Eu _x BO ₅ (where 0.01 ≦ x ≦ 1.0) used in the white light-emitting element of this example are nitrogen starting materials. It can be manufactured by a solid phase reaction method or a coprecipitation method, for example, by baking in a gas atmosphere. As an example, taking a production method of the red light-emitting phosphor LiLa _1.8 Eu _0.2 BO _{5 having} the above composition (x = 0.2) as an example, first, Li as a starting material has a purity of 99.99% or more. the ₂ CO ₃ reagent and _La 2 _{O 3} reagent and a purity of 99.99% or more _H 3 BO ₃ or _B 2 _{O 3} reagent and a purity of 99.9% or higher _Eu 2 _{O 3} reagent so that the above composition ratio Mix. That is, Li ₂ CO ₃ , La ₂ O ₃ , B ₂ O ₃ and Eu ₂ O ₃ are prepared so that the molar ratio of Li, La, B and Eu is 1: 1.8: 1: 0.2. . Thereafter, these are dry-mixed and fired at about 800 ° C. to 1100 ° C. for several hours (about 3 hours), whereby a red light emitting phosphor having the above composition (x = 0.2) can be produced. . The yellow phosphor YAG: Ce can also be manufactured in the same manner as described above by using oxides of Y, Gd, Ce, Al, and Ga as raw materials.

The red light-emitting phosphor LiLa _2-x Eu _x BO ₅ was LiLa _1.8 Eu _0.2 BO ₅ having a composition value x = 0.2, and the composition value x was 0.01 ≦ x ≦ 1. Any composition may be used within the range of 0. The red light-emitting phosphor composed of a lithium borate phosphor represented by the general formula, LiLa _2-x Eu _x BO ₅ (where 0.01 ≦ x ≦ 1.0) has a composition value x. Is less than the lower limit of 0.01, sufficient light emission intensity cannot be obtained. On the other hand, if the composition value x exceeds 1.0, which is the upper limit, the emission intensity decreases due to concentration quenching, and the practicality is lost. In addition, the excitation intensity in the vicinity of the wavelength of 460 nm to 470 nm also varies to some extent depending on the composition value x, but the conventional red light emitting phosphor Y ₂ O ₂ S in the range of the composition value x 0.01 ≦ x ≦ 1.0. : Greater than Eu. For this reason, the composition value x of the LiLa _2-x Eu _x BO ₅ phosphor is 0.01 ≦ x ≦ 1.0.

  In the first embodiment, the phosphor is dispersed and enclosed in the transparent resin 4. However, the phosphor may be dispersed and enclosed in the transparent substrate 3 without dispersing the phosphor in the transparent resin. .

The white light-emitting device of Example 2 is composed of a lithium borate phosphor blended with a YAG: Ce phosphor (yellow light-emitting phosphor) and a Li _2-x Eu _x B ₂ O ₄ phosphor (however, , 0.01 ≦ x ≦ 1.0). Specifically, a Li _1.8 Eu _0.2 B ₂ O ₄ phosphor having a composition value x of 0.2 was used.

FIG. 3 is a cross-sectional view of the white light emitting device of this example. As shown in FIG. 3, the white light-emitting element of this example has a configuration in which a blue light-emitting diode 1 is installed on a lead frame 5 and sealed with a transparent resin 4, unlike Example 1. In the transparent resin 4, a phosphor in which a powdery YAG: Ce phosphor 2 a and a red light emitting phosphor Li _1.8 Eu _0.2 B ₂ O ₄ 2 c are blended is dispersed and enclosed.

The lithium borate phosphor Li _1.8 Eu _0.2 B ₂ O ₄ 2c used for the red light-emitting phosphor in Example 2 has the characteristics shown in FIG.

FIG. 4 shows an excitation spectrum (curve 32) of the Li _1.8 Eu _0.2 B ₂ O ₄ phosphor 2c, which is a red light-emitting phosphor used in the white light-emitting element in this example, and white light emission conventionally. red light emitting phosphor has been used in the element Y _{2 O 2 S:} is a diagram showing the excitation spectrum (curve 33) of Eu. In the figure, the horizontal axis represents wavelength and the vertical axis represents excitation intensity. As is clear from the figure, the red light-emitting phosphor of this example is the same as the conventional red light-emitting phosphor Y ₂ O ₂ S: Eu in the vicinity of 460 nm to 470 nm, which is the light emission wavelength of the blue light-emitting diode 1. It can be seen that the excitation and emission efficiencies are about the same as those of the Y ₂ O ₂ S: Eu phosphor.

The Y ₂ O ₂ S: Eu phosphor has a deep red emission color and low brightness. On the other hand, the light emission color of the Li _1.8 Eu _0.2 B ₂ O ₄ phosphor of Example 2 is more yellowish than the Y ₂ O ₂ S: Eu phosphor and is vermilion. Near red, and the brightness is higher than that of the Y ₂ O ₂ S: Eu phosphor. For this reason, even if the excitation intensity of the Li _1.8 Eu _0.2 B ₂ O ₄ phosphor is comparable to that of the Y ₂ O ₂ S: Eu phosphor, the white light-emitting element of Example 2 is Brighter than white light emitting elements using Y ₂ O ₂ S: Eu phosphor and excellent in color rendering.

The Li _1.8 Eu _0.2 B ₂ O ₄ phosphor 2c can be manufactured in the same manner as in Example 1. Specifically, Li ₂ CO ₃ reagent having a purity of 99.99% or more, H ₃ BO ₃ or B ₂ O ₃ reagent having a purity of 99.99% or more, and Eu ₂ O having a purity of 99.9% or more are used as starting materials. _Three reagents are prepared so as to achieve the above composition ratio. That is, Li ₂ CO ₃ , H ₃ BO ₃ , and Eu ₂ O ₃ are prepared so that the molar ratio of Li, B, and Eu is 1.8: 2: 0.2. Thereafter, these are dry-mixed and fired at about 600 ° C. to 900 ° C. for several hours (about 3 hours), whereby a red light emitting phosphor having the above composition (x = 0.2) can be produced.

As the red light-emitting phosphor Li _2-x Eu _x B ₂ O ₄ , Li _1.8 Eu _0.2 B ₂ O ₄ having a composition value x = 0.2 was used, but the composition value x was 0.01 ≦ Any composition may be used as long as x ≦ 1.0. Similar to Example 1, a red light-emitting fluorescent substance composed of a lithium borate-based phosphor represented by the general formula, Li _2-x Eu _x B ₂ O ₄ (where 0.01 ≦ x ≦ 1.0) When the composition value x is lower than 0.01 which is the lower limit of the body, sufficient light emission intensity cannot be obtained. On the other hand, if the composition value x exceeds 1.0, which is the upper limit, the emission intensity decreases due to concentration quenching, and the practicality is lost. For this reason, the composition value x of the Li _2-x Eu _x B ₂ O ₄ phosphor is 0.01 ≦ x ≦ 1.0.

  As shown in FIG. 5, the third embodiment is an example in which the resin sealing structure of the blue light emitting diode 1 is different from the second embodiment and is molded by combining two types of mold resins.

In the white light emitting device of Example 3, the blue light emitting diode 1 is mounted and fixed on the cup-shaped mounting portion 5a of the lead frame 5, and the powdery yellow light emitting phosphor 22 and the red light emitting phosphor 21 are mixed. The first resin 41 dispersed encloses the blue light-emitting diode and seals the mounting portion so as not to protrude from the cup-shaped mounting portion 5a, and the first resin 41 is transparent with the first resin 41. The resin 41 and the cup-shaped mounting portion 5a of the lead frame 5 are surrounded and sealed. As the red light emitting phosphor 21, the LiLa _1.8 Eu _0.2 BO ₅ phosphor of Example 1 or the Li _1.8 Eu _0.2 B ₂ O ₄ phosphor of Example 2 was used. The yellow light emitting phosphor 22 was a YAG: Ce phosphor.

  In the third embodiment, the second resin 42 is a transparent resin. However, the second resin 42 has a light scattering function by dispersing and encapsulating a light scattering material or by roughening the second resin surface. It is good also as resin.

  Unlike the second embodiment, the white light-emitting element of the third embodiment has the first resin 41 in which the phosphor is dispersed in the cup-shaped mounting portion of the lead frame 5. When a large number of the light emitting elements are arranged, it is possible to prevent light leaking from the adjacent light emitting elements from being blocked by the cup-shaped mounting portion and reaching the phosphor. For this reason, there exists an advantage which can prevent that a fluorescent substance is excited and light-emitted by the light emission leaked from the adjacent light emitting element. That is, it is possible to prevent the light-emitting element that has been turned off from being turned on by the light from the adjacent light-emitting element, and to prevent the light-emitting element that has been turned off from being mistakenly turned on.

  Example 4 is an example of molding with two types of resins, as in Example 3. However, Example 3 is different from Example 3 in that a yellow light-emitting phosphor and a red light-emitting phosphor are sealed in separate resins. Is different.

As shown in FIG. 6, the white light emitting element of Example 3 has a blue light emitting diode 1 mounted and fixed on a stem 6, and blue light is emitted by a first resin 43 in which a YAG: Ce phosphor 2a is dispersed. The diode 1 is surrounded and sealed, and the first resin 43 is surrounded and sealed by the second resin 44 in which the red light emitting phosphor 21 is dispersed. The second resin surface is roughened to have a light scattering structure so that blue, yellow, and red light emission colors are sufficiently mixed and visually recognized. The red light emitting phosphor 21 uses the LiLa _1.8 Eu _0.2 BO ₅ phosphor of Example 1 or the Li _1.8 Eu _0.2 B ₂ O ₄ phosphor of Example 2.

  The fourth embodiment has an advantage that the color rendering properties can be easily adjusted by adjusting the thickness of the double mold resin at the time of manufacturing the white light emitting element.

  In Example 4, the resin in which the blue light-emitting diode 1 is molded has a two-layer structure, but it may have a multilayer structure of three or more layers.

  FIG. 7 shows a cross-sectional view of the white light emitting element of Example 5 (bonding lines are not shown).

  As shown in the figure, the white light-emitting element of Example 5 has two blue light-emitting diodes 1a and 1b arranged side by side on the stem 6, and one of the blue light-emitting diodes 1a is dispersed with a red light-emitting phosphor 21. The other blue light emitting diode 1b is sealed with a resin 43 in which a yellow light emitting phosphor YAG: Ce2a is dispersed, and the whole is sealed with a third resin 45 so that one of the blue light emitting diodes 1b is sealed. The red light emitting phosphor is excited and emitted by the light emission of the diode 1a, and the yellow light emitting phosphor YAG: Ce is excited and emitted by the light emission of the other blue light emitting diode 1b. The third resin 45 has a light scattering structure in which the light scatterer 9 is dispersed / encapsulated or the surface is roughened, so that the emission color is not visually recognized independently. As the red light-emitting phosphor 21, the lithium borate phosphor used in Example 1 or Example 2 was used.

  The fifth embodiment has an advantage that the color rendering properties can be controlled by an external driving circuit because the luminances of red, yellow and blue can be independently controlled by individually controlling the driving current of each blue light emitting diode.

  FIG. 8 shows a cross-sectional view of the white light-emitting element of Example 6.

  As shown in FIG. 8, the white light emitting element of Example 6 has a fluorescent layer coating on the light extraction surface of the blue light emitting diode. The blue light emitting diode has a semiconductor laminated structure including a light emitting region 14 in which an n-type gallium nitride semiconductor layer 12 and a p-type gallium nitride semiconductor layer 13 are laminated on a sapphire substrate 11. A transparent electrode 15 is provided on the light extraction surface of the semiconductor laminated structure, and a p-electrode 16 is formed in contact with the transparent electrode 15. The n electrode 17 is formed on the exposed surface of the n-type gallium nitride based semiconductor layer. A fluorescent layer 18 is formed on the transparent electrode 15.

The phosphor layer 18 is composed of a single phosphor layer formed by forming a phosphor that is a mixture of a yellow light-emitting phosphor and a red light-emitting phosphor, or a phosphor layer that is formed with a yellow light-emitting phosphor. A phosphor layer having a multilayer structure in which a phosphor layer and a phosphor layer on which a red light emitting phosphor is formed may be laminated. Further, it is composed of a resin layer or a passivation film (for example, SiO ₂ film) in which a phosphor mixed with a yellow light-emitting phosphor and a red light-emitting phosphor is dispersed and encapsulated, that is, contains a phosphor. You may comprise a fluorescent layer with a member. Also in this case, a fluorescent layer having a multilayer structure in which a layer containing a yellow light-emitting phosphor and a layer containing a red light-emitting phosphor are laminated may be used. As a method for forming these fluorescent layers, various vapor deposition methods such as sputtering, spin coating with a dispersion in an organic solvent or resin, screen printing, a method of applying a phosphor chiller, etc. A method is available.

In this embodiment, a yellow light-emitting phosphor and a red light-emitting phosphor are mixed in siloxane, and applied and formed on a transparent electrode with a spinner, and a phosphor layer composed of a SiO ₂ film in which the phosphor is dispersed. A passivation film was also formed. As the red light emitting phosphor, the LiLa _1.8 Eu _0.2 BO ₅ phosphor of Example 1 or the Li _1.8 Eu _0.2 B ₂ O ₄ phosphor of Example 2 was used. A yellow light emitting phosphor was a YAG: Ce phosphor.

  In Example 6, the fluorescent layer was uniformly formed on the entire upper surface of the transparent electrode. However, when the fluorescent layer is formed in a stripe shape or a lattice shape to form a region not covered with the fluorescent layer, blue light is emitted. Can be adjusted.

  The blue light emitting diode used in each example may be of any material and structure as long as it emits blue light having a main peak wavelength of the emission spectrum of 450 nm to 480 nm, preferably around 460 nm to 470 nm. As an example, in the above embodiment, an n-type GaN cladding layer, an MQW active layer in which AlGaN quantum well layers and GaN barrier layers are alternately stacked, a p-type AlGaN cladding layer, and a p-type GaN contact layer are sequentially stacked on a sapphire substrate. A multilayer structure was used. Electrodes are provided on the n-type GaN cladding layer and the p-type GaN contact layer, respectively.

  The white light emitting device of the above example has a structure in which a blue light emitting diode is embedded in a transparent resin. However, the blue light emitting diode is not sealed with the blue light emitting diode, and the blue light emitting device is provided in a case having a window mixed with phosphor powder. The phosphor is excited by blue light emitted from the blue light emitting diode, such as a structure in which a phosphor or a member containing the phosphor is arranged in front of the emission surface of the blue light emitting diode, such as a structure in which a diode is installed. Any structure may be used as long as the structure emits light.

In any of the above examples, the yellow light-emitting phosphor is a YAG-based phosphor. However, if the yellow light-emitting phosphor absorbs blue light and emits yellow light, for example, a perylene-based phosphor, Any yellow light emitting phosphor such as an aluminate phosphor, a phosphate phosphor, a silicate phosphor, or a ZnS-based phosphor may be used. Specific examples by way of example, the silicate phosphor _{(Sr 1-a-b-} y Ba a Ca b Eu y) 2 SiO 4 fluorescers (where, 0 ≦ a ≦ 0.3,0 ≦ For b ≦ 0.6, 0 <y <1), ZnS: Ag, Cl, ZnS: Cu, Al, or the like can be used as the ZnS-based phosphor.

  The white light-emitting element of the present invention is used for white light sources such as dots and columns, display devices such as level meters, characters and symbols, lighting devices such as lamps, backlights of liquid crystal display devices, and illuminations. it can.

Sectional drawing of the white light emitting element of Example 1. Shows characteristics of _LiLa 1.8 _Eu 0.2 BO ₅ phosphor used for a white light emitting element Sectional drawing of the white light emitting element of Example 2. Shows characteristics of _Li 1.8 _Eu 0.2 _B 2 _{O 4} phosphor used for a white light emitting element Sectional drawing of the white light emitting element of Example 3. Sectional drawing of the white light emitting element of Example 4. Sectional drawing of the white light emitting element of Example 5. Sectional drawing of the white light emitting element of Example 6.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Blue light emitting diode 1a Blue light emitting diode 1b Blue light emitting diode 2a YAG: Ce phosphor 2b LiLa _1.8 Eu _0.2 BO ₅ phosphor 2c Li _1.8 Eu _0.2 B ₂ O ₄ phosphor 21 Red light emitting phosphor 22 Yellow light emitting phosphor 3 Transparent substrate 4 Transparent resin 4a Surface 5 Lead frame 5a Mounting portion 6 Stem 9 Light scatterer 11 Sapphire substrate 12 N-type gallium nitride semiconductor layer 13 p-type gallium nitride semiconductor Layer 14 Light emitting region 15 Transparent electrode 16 P electrode 17 N electrode 18 Fluorescent layer 41 First resin 42 Second resin 43 First resin 44 Second resin 45 Third resin

Claims (9)

  A blue light emitting diode chip, a yellow light emitting phosphor that emits yellow fluorescent light when excited by blue light from the blue light emitting diode chip, and a red fluorescent light excited by blue light from the blue light emitting diode chip A white light-emitting element having a red light-emitting phosphor that emits light, wherein a lithium borate-based phosphor using europium as an activator is used as the red light-emitting phosphor. _2. The white color according to claim 1, wherein the lithium borate phosphor using europium as an activator is LiLa _2-x Eu _x BO ₅ (where 0.01 ≦ x ≦ 1.0). Light emitting element. 2. The lithium borate phosphor using europium as an activator is Li _2-x Eu _x B ₂ O ₄ (where 0.01 ≦ x ≦ 1.0). White light emitting element.   The white light-emitting element according to claim 1, wherein the yellow light-emitting phosphor is a YAG: Ce phosphor.   The white light-emitting element according to claim 1, wherein the yellow light-emitting phosphor and the red light-emitting phosphor are in a spatially separated position.   6. The mold resin containing a yellow light-emitting phosphor and the mold resin containing a red light-emitting phosphor cover the blue light-emitting diode chip and are alternately laminated in layers. The white light emitting element in any one.   Having two blue light emitting diode chips, one blue light emitting diode chip emits light to excite and emit red light, and the other blue light emitting diode chip emits light to excite and emit yellow light emitting phosphor. The white light emitting element according to claim 1, wherein:   6. The white light emitting device according to claim 1, wherein a fluorescent layer is provided on the uppermost layer of a blue light emitting diode chip having a semiconductor multilayer structure including a light emitting region. 9. The white light emitting device according to claim 8, wherein the fluorescent layer provided on the uppermost layer of the blue light emitting diode chip having a semiconductor multilayer structure including the light emitting region is a passivation film containing a fluorescent material.

Images