Wavelength converter and light source for generating white light

The present invention is a light emitting device having a light emitting element, and in particular, the light emitting element emits light in a first spectral region, and a group of alkaline earth metal orthosilicates. The present invention relates to a light emitting device derived from or containing at least this group of phosphors, absorbing a part of the light emission of the light emitting element, and further having a phosphor that emits light in another spectral region.

[0002] The light emitting device is, for example, an inorganic LED, an organic LED, a laser diode, an inorganic thick film electroluminescence sheet, or an inorganic thin film electroluminescence component.

[0003] LEDs are particularly prominent in that they have a long life, are space-saving, are shock-resistant, and emit light in a narrower spectral band.

[0004] A large number of emission colors, a large number of emission colors in a particularly wide spectral band, cannot be realized or can only be realized inefficiently by the inherent emission of the active semiconductor material in the case of LEDs. This is especially true when obtaining white luminescence.

[0005] According to known technical standards, emission colors that cannot be originally realized by semiconductors can be obtained by color conversion technology.

[0006] In essence, this color conversion technique is based on the following principle: that is, at least one phosphor is placed on the LED die. The phosphor absorbs the light emitted by the die and then emits photoluminescent light in a different emission color.

[0007] Basically, an organic system can be used as the phosphor, or an inorganic system can be used. The essential advantage of inorganic pigments is that they are more environmentally resistant than organic pigments. Inorganic systems are advantageous in relation to the long life of inorganic LEDs, and therefore when considering color stability.

[0008] With respect to ease of processing, it is advantageous to use an inorganic fluorescent pigment instead of an organic fluorescent coating system that has an excessively long growth period (Wachstumzeiten) to obtain the required film thickness. Is clear. The pigment is placed in a matrix and further placed on an LED die.

[Problems to be Solved by the Invention] At present, in many cases, materials from YAGs are used as pigments for color conversion because the number of inorganic materials satisfying the above requirements is small. To. However, this material has the disadvantage that it exhibits high efficiency only when the material has a maximum emission value of less than 560 nm. For this reason, YAG pigments combined with a blue diode (450 to 490 nm) can be used to achieve only a cold white emission color. Especially for use in the lighting field, there are even higher requirements for light sources in terms of color temperature and color reproduction, which are not met by the white LEDs currently in use.

[0010] Furthermore, from WO 00/33389, in order to obtain a light close to white using a blue LED, especially Ba₂SiO₄:EU²⁺Is known to be used as a phosphor. Ba₂SiO₄:EU²⁺The emission of light is at 505 nm, a relatively short wavelength, so that this light is significantly colder.

[0011] In the paper by SHM Poort et al., Optical properties of Eu2 + -aktivated.297, Eu²⁺Activated Ba₂SiO₄And phosphates such as KBaPO₄And KSrPO₄The nature of is being studied. In the same document, Ba₂SiO₄It has been confirmed that the emission of is at 505 nm. The luminescence of the two phosphates studied is essentially at shorter wavelengths (420 nm to 430 nm).

[0012] An object of the present invention is to reproduce different light colors and high colors with a high optical luminescence effect by the above-mentioned light emitting device by remarkably good absorption of ultraviolet rays or blue radiation of a first light source by a phosphor. In this case, the position of the color in the CIE-deviation ellipse commonly used as a light source for general lighting is within the range of very close color temperatures between about 2600K and 7000K. It is especially advantageous to be in.

[Means for Solving the Problems] The above problems are solved by the light emitting device of the present invention. According to the present invention, it is composed of a nitride semiconductor.<u style="single">Blue LED element with emission wavelength of 450 to 490 nm</u>And the above<u style="single">LED element</u>In a light emitting device including a phosphor that absorbs a part of the light emitted by the light and emits light having a wavelength different from the wavelength of the absorbed light, the phosphor is expressed by the formula: (2-xy) SrO. x (Ba, Ca) O · (1-abcd) SiO₂ AP₂O₅ bAl₂O₃ cB₂O₃ dGeO₂: y Eu²⁺Alkaline earth metal silicates activated with divalent europium represented by (in the formula, 0 <x <1.6, 0.005 <y <0.5, 0 a, b, c, d <0.5) and / Or (2-xy) BaO x (Sr, Ca) O (1-abcd) SiO₂ AP₂O₅ bAl₂O₃ cB₂O₃ dGeO₂: y Eu²⁺Consists of a divalent europium-activated alkaline earth metal silicate represented by 0.01 <x <1.6, 0.005 <y <0.5, 0a, b, c, d <0.5 in the formula) Includes a first phosphor and a second phosphor that emits red light<u style="single">See,</u><u style="single">A light emitting device that emits white light having a color temperature in the range of 2600K and 7000K and having a Ra value> 72 is provided.</u><u style="single">In this case, at least one of the values a, b, c and d is advantageously greater than 0.01.</u><u style="single">That is, it was surprisingly found that when strontium silicate or a mixed form of barium silicate and strontium orthosilicate silicate is used instead of barium silicate, the wavelength of emitted light becomes longer. Germanium substitution of silicon part as well as additional P</u>_{<u style="single">2</u>}<u style="single">O</u>_{<u style="single">3</u>}<u style="single">, Al</u>_{<u style="single">2</u>}<u style="single">O</u>_{<u style="single">3</u>}<u style="single">And / or B</u>_{<u style="single">2</u>}<u style="single">O</u>_{<u style="single">3</u>}<u style="single">Also has an effect on the emission spectrum, so that the emission spectrum can be optimally adjusted for each use case.</u><u style="single">Advantageously, the light emitting device is another phosphor from the group of alkaline earth metal aluminates activated with divalent europium and / or manganese and / or Y (V, P, Si) O.</u>_{<u style="single">4</u>}<u style="single">: Eu or</u><u style="single">Me (3-xy) MgSi</u>_{<u style="single">2</u>}<u style="single">O</u>_{<u style="single">3</u>}<u style="single">: xEu, yMn</u><u style="single">(During the ceremony</u><u style="single">0.005 <x <0.5,</u><u style="single">0.005 <y <0.5,</u><u style="single">Me stands for Ba and / or Sr and / or Ca)</u><u style="single">Alkaline earth metal-magnesium-disilicate: Eu</u>^{<u style="single">2+</u>}<u style="single">, Mn</u>^{<u style="single">2+</u>}<u style="single">It has yet another red-emitting phosphor from the group of.</u><u style="single">In addition, small amounts of monovalent ions, especially halides, were found to be advantageous for crystallinity and emissivity when incorporated into the phosphor lattice.</u><u style="single">Advantageously, the light emitting device emits white light having a Ra value> 72.</u>[0014] Further, according to the present invention, it is composed of a GaN-based semiconductor arranged in a cup of a mount reed.<u style="single">Blue LED element with emission wavelength of 450 to 490 nm</u>And the above<u style="single">LED element</u>A fluorescent substance that absorbs a part of the light emitted by the light and emits light having a wavelength different from the wavelength of the absorbed light, and a coating member in which a sealing agent containing the fluorescent substance is filled in the cup. In a light emitting device including the coating member, the light emitting element, and a mold member covering the tip of the mount lead, the phosphor is of the formula: (2-xy) SrO · x (Ba, Ca) O · ( 1-abcd) SiO₂ AP₂O₅ bAl₂O₃ cB₂O₃ dGeO₂: y Eu²⁺Alkaline earth metal silicates activated with divalent europium represented by (in the formula, 0 <x <1.6, 0.005 <y <0.5, 0 a, b, c, d <0.5) and / Or (2-xy) BaO x (Sr, Ca) O (1-abcd) SiO₂ AP₂O₅ bAl₂O₃ cB₂O₃ dGeO₂: y Eu²⁺Consists of a divalent europium-activated alkaline earth metal silicate represented by 0.01 <x <1.6, 0.005 <y <0.5, 0a, b, c, d <0.5 in the formula) Includes a first phosphor and a second phosphor that emits red light<u style="single">See,</u><u style="single">A light emitting device is provided that has a color temperature in the range of 2600K and 7000K and emits white light having a Ra value> 72.</u>[0015] Further, according to the present invention, the GaN-based compound semiconductor is flip-chip mounted in a housing.<u style="single">Blue LED with emission wavelength of 450 to 490 nm</u>Chi<u style="single">With</u>The LED chip is arranged by a phosphor that absorbs a part of the light emitted by the LED chip and emits light having a wavelength different from the wavelength of the absorbed light, and a transparent sealing agent containing the phosphor. In a light emitting device having a molded member that fills the inside of the provided housing, the phosphor is of the formula: (2-xy) SrO · x (Ba, Ca) O · (1-abcd) SiO.₂ AP₂O₅ bAl₂O₃ cB₂O₃ dGeO₂: y Eu²⁺Alkaline earth metal silicates activated with divalent europium represented by (in the formula, 0 <x <1.6, 0.005 <y <0.5, 0 a, b, c, d <0.5) and / Or (2-xy) BaO x (Sr, Ca) O (1-abcd) SiO₂ AP₂O₅ bAl₂O₃ cB₂O₃ dGeO₂: y Eu²⁺Consists of a divalent europium-activated alkaline earth metal silicate represented by 0.01 <x <1.6, 0.005 <y <0.5, 0a, b, c, d <0.5 in the formula) Includes a first phosphor and a second phosphor that emits red light<u style="single">See,</u><u style="single">A light emitting device is provided that has a color temperature in the range of 2600K and 7000K and emits white light having a Ra value> 72.</u>[Embodiment of the Invention] According to the first embodiment of the present invention, the light emitting device has two different phosphors, in which case at least one of them is an alkaline earth metal ortho. It is a silicate phosphor. In this way, the color tone of white can be adjusted particularly accurately.

[0017] There are many possibilities for the mechanical implementation of the light emitting device according to the present invention. According to one embodiment, one or more LED chips are arranged on a substrate in the reflector and the phosphor is dispersed in a lens arranged on the reflector.

[0018] However, it is also possible that one or more LED chips are arranged on a substrate in the reflector and a phosphor is applied to the reflector.

Advantageously, the LED chip is filled with a transparent sealing compound having a dome-like shape. The sealing compound, on the one hand, forms mechanical protection, and on the other hand, the sealing compound further improves the optical properties (improved emission of LED die light).

The phosphor may be dispersed in the encapsulating compound, which allows the LED chip and polymer lens disposed on the substrate to contain as little gas as possible. Combined, in this case the polymer lens and the encapsulating compound have up to 0.1 different refractive indexes. The LED die may be directly confined by the encapsulating compound, however, the LED die is filled with a transparent encapsulating compound (ie, in this case a transparent encapsulating compound and fluorophore). There is also a sealing compound containing). Due to the approximate index of refraction, there is almost no loss due to reflection at the interface.

Advantageously, the polymer lens has a spherical or elliptical recess, which is filled with the sealing compound, so that the LED array is at a short distance from the polymer lens. It is fixed. In this way, the size of the mechanical structure can be reduced.

It is advantageous that the fluorophore is advantageously suspended in an inorganic matrix in order to achieve a uniform distribution of the fluorophore.

[0023] When two fluorophores are used, the two fluorophores are suspended in their respective matrices, in which case these matrices are placed one after the other in the direction of light propagation. It is advantageous to be there. This allows the concentration of the matrix to be reduced as compared to the case where different fluorophores are dispersed together.

[0024] Next, an important step of producing a phosphor according to the first embodiment of the present invention will be described.

[0025] For the production of silicate phosphors, the starting materials alkaline earth metal carbonates, silicon dioxide and europium oxide are densely mixed according to the composition selected and the fluorophore It is a solid reaction commonly used in production and is converted to the desired phosphor at temperatures of 1100 ° C and 1400 ° C in a reducing atmosphere. In this case, it is advantageous for the crystallinity to add ammonium chloride or other halide in a small proportion to the reaction mixture, preferably in proportions less than 0.2 mol. If desired, part of silicon can be replaced with germanium, boron, aluminum, phosphorus, or part of europium can be replaced with manganese, which is the element that decomposes into oxides by heat. It is carried out by adding an appropriate amount of the compound of. In this case, the range of reaction conditions is maintained.

[0026] The obtained silicate emits at a wavelength of 510 nm to 600 nm and has a half width up to 110 nm.

Alkaline earth metal aluminates activated by the use of one of the phosphors from the above group or in combination from the above group, or with divalent europium and / or manganese, and Y (V, P, Si) O₄:EU²⁺Yet another red-emitting phosphor from the group of, Y₂O₂S: Eu³⁺In combination with a common fluorophore from the group of fluorophores, luminescent colors with defined color temperatures and high color reproducibility can be obtained, as shown in the following examples. Is.

[0028] T = 2778K (464nm + Sr)_1.4Ba_0.6SiO₄:EU²⁺); x = 0.4619, y = 0.4247, Ra = 72, T = 2950K (464nm + Sr)_1.4Ba_0.6SiO₄:EU²⁺); x = 0.4380, y = 0.4004, Ra = 73, T = 3497K (464nm + Sr)_1.6Ba_0.4SiO₄:EU²⁺); x = 0.4086, y = 0.3996, Ra = 74, T = 4183K (464nm + Sr)_1.9Ba_0.08Ca_0.02SiO₄:EU²⁺); x = 0.3762, y = 0.3873, Ra = 75, T = 6624K (464nm + Sr)_1.9Ba_0.02Ca_0.08SiO₄:EU²⁺); x = 0.3101, y = 0.3306, Ra = 76, T = 6385K (464nm + Sr)_1.6Ba_0.4SiO₄:EU²⁺+ Sr_0.4Ba_1.6SiO₄:EU²⁺); x = 0.3135, y = 0.3397, Ra = 82, T = 4216K (464nm + Sr)_1.9Ba_0.08Ca_0.02SiO₄:EU²⁺<u style="single">);</u>x = 0.3710, y = 0.3696, Ra = 82,<u style="single">T =</u>3954K (464nm + Sr_1.6Ba_0.4SiO₄:EU²⁺+ Sr_0.4Ba_1.6SiO₄:EU²⁺+ YVO4: Eu³⁺); x = 0.3756, y = 0.3816, Ra = 84, T = 6489K (464nm + Sr)_1.6Ba_0.4SiO₄+ Sr_0.4Ba_1.6SiO₄:EU²⁺+ Barium Magnesium Aluminate: Eu²⁺); x = 0.3115, y = 0.3390, Ra = 66, T = 5097K (464nm + Sr)_1.6Ba_0.4(Si_0.08B_0.02) O₄:EU²⁺+ Sr_0.6Ba_1.4SiO₄:EU²⁺); x = 0.3423, y = 0.3485, Ra = 82, T = 5084K (464nm + Sr)_1.6Ba_0.4(Si_0.08B_0.02) O₄:EU²⁺+ Sr_0.6Ba_1.4SiO₄:EU²⁺+ Strontium aluminate magnesium: Eu²⁺); x = 0.3430, y = 0.3531, Ra = 83, T = 3369K (464nm + Sr)_1.4Ba_0.6Si_0.95Ge_0.05O₄:EU²⁺); x = 0.4134, y = 0.3959, Ra = 74, T = 2787K (466nm + Sr)_1.4Ba_0.6Si_0.98P_0.02O_4.01:EU²⁺); x = 0.4630, y = 0.4280, Ra = 72, T = 2913K (464nm + Sr)_1.4Ba_0.6Si_0.98Al_0.02O₄:EU²⁺); x = 0.4425, y = 0.4050, Ra = 73.

[0029] In the case of one embodiment of the present invention, the color conversion is carried out as follows.

Assemble one or more LED chips on the board. Directly on the LED (on the one hand to protect the LED chip and on the other hand to allow better emission of the light generated within the LED chip), the encapsulating material is hemispherical or semi-elliptical. Arrange in the form of. The encapsulating material may include each die individually, or the encapsulating material may be a common single form for all LEDs. The substrate thus equipped is placed in the reflector or the reflector is placed on the LED chip.

[0031] A lens is installed on the reflector. On the one hand, the lens is used to protect the device, and on the other hand, a fluorescent pigment is mixed into the lens. In this way the lens gives the impression of an opaque and yellow color. The blue light (including ultraviolet light) passing through the lens is converted into long-wave light (yellow light) when passing through the optical component. As a result, the impression of a white color is obtained by combining blue light and yellow light. The loss due to the waveguide, for example between plane parallel plates, is reduced by the opacity and diffusivity of the lens. In addition, the reflector allows only light that has already been adjusted to enter the lens, so that total internal reflection is reduced from the beginning.

[0032] Separately, a reflector may be placed on each LED chip, the reflector is filled in a dome shape, and the lens is on each reflector or this device. Placed on top of the whole.

[0033] It is advantageous to use LED arrays instead of single LEDs to manufacture lighting equipment. In the case of another embodiment of the present invention, the color conversion is carried out in an LED array in which the LED chips are assembled directly on the substrate as follows.

[0034] The LED array is adhered to a transparent polymer lens made of another material (eg PMMA) using a sealing compound (eg epoxy resin). The materials of the polymer lens and the encapsulating compound are selected to have a refractive index as close as possible, i.e. phase-matched. The encapsulating compound resides in the largest spherical or oval recess of the polymer lens. The shape of this recess is important in that the color-converting material is dispersed in the encapsulating compound, and thus this shape ensures that an angle-independent emission color is obtained. Can be done. Separately, the array can be filled with a clear encapsulating compound and subsequently adheres to the polymer lens with the encapsulating compound containing a color transformant. Can be done.

[0035] For LEDs with particularly good color reproducibility in which at least two different fluorophores are used, these fluorophores are dispersed separately rather than dispersed together in one matrix. And it is advantageous to stack them. This is especially true for combinations where the final emission color is obtained by multiple color conversion processes. That is, the longest wave emission color is produced by one emission process, in which case the emission process proceeds as follows: That is, the absorption of LED emission by the first phosphor, the first. Light emission of the first phosphor, absorption of the light emission of the first phosphor by the second phosphor, and light emission of the second phosphor. In particular, for this type of process, it is advantageous to place each fluorophore in phase with each other in the direction of light propagation, because it disperses the various fluorophores in a single manner. It is possible to reduce the concentration of the phosphor as compared with the case where

[0036] The present invention is not limited to the above examples. The phosphor may be incorporated in a polymer lens (or another optical component). The fluorophore can be placed directly on the LED die or on the surface of a transparent encapsulating compound. The phosphor can also be incorporated into one matrix together with the dispersed particles. This prevents sedimentation in the matrix and ensures uniform light emission.

[0037] Hereinafter, an example in which the above-mentioned phosphor having a photoluminescence effect is used for a light emitting diode (LED) lamp will be described in more detail.

[0038] FIG. 1 is a schematic cross-sectional view of an LED lamp according to a second embodiment of the light emitting device of the present invention, and shows a so-called lens type LED lamp. The blue LED 4 made of a GaN-based semiconductor is attached via a mount 5 to a metal stem 3 forming a cup 10 that acts as a reflector so as to reflect the light emitted from the blue LED 4 above the LED lamp. One electrode of the blue LED 4 and the lead frame 2 are connected by a gold bonding wire 7, and the other electrode and the lead frame 1 are connected by a gold bonding wire 6. In order to fix the blue LED 4, the inside of the cup 10 is covered with the internal resin 8 which is a coating member. Further, the lead frame 1 on which the lead frame 2 and the metal stem 3 are formed is sealed with the external resin 9 which is a mold member. Therefore, the blue LED 4 has an internal resin 8 and an external resin 9.<u style="single">To</u>More double sealed. The metal stem 3 and the lead frame 1 are also referred to as mount leads. A detailed description of the blue LED 4 will be described later.

[0039] The internal resin 8 containing the phosphor 11 is filled inside the cup 10 below the horizontal plane of the upper edge of the cup 10. As a result, when a plurality of LEDs are arranged close to each other, color mixing between the LEDs does not occur, and a flat display can be realized with the LEDs to obtain an image with good resolution.

[0040] As the internal resin 8, a silicone resin or epoxy resin that becomes transparent after solidification is used. Further, the internal resin 8 is mixed with a phosphor 11 containing the above-mentioned divalent europium-activated alkaline earth metal orthosilicate and / or alkaline earth metal orthosilicate as a main component. As described above, the phosphor 11 has a photoluminescence effect, absorbs the light emitted by the blue LED 4, and emits light having a wavelength different from the wavelength of the absorbed light.

[0041] In addition, low melting point glass may be used instead of the silicone resin or epoxy resin used as the internal resin 8. The low melting point glass has excellent moisture resistance and can prevent harmful ions from entering the blue LED4. Furthermore, since the light emitted from the blue LED 4 can be transmitted as it is without being absorbed, it is not necessary to anticipate the absorption and strongly emit light.

[0042] Further, the diffusing material may be further mixed in the silicone resin, the epoxy resin, or the low melting point glass which is the internal resin 8 in which the phosphor 11 is mixed. Since the diffuser diffuses the emitted light from the blue LED 4 into scattered light, the light from the blue LED 4 can easily hit the phosphor 11 and the amount of light emitted from the phosphor 11 can be increased. The diffusing material is not particularly limited, and a well-known substance can be used.

[0043] As the external resin 9, an epoxy resin that becomes transparent after solidification can be used.

[0044] Various resins such as epoxy resin can be used for the mount 5 for ease of handling. The resin used for the mount 5 is preferably a resin having adhesiveness and also having an insulating property so that even if the mount 5 rises on the side surface of the extremely small blue LED 4, each layer does not short-circuit on the side surface.

[0045] The mount 5 uses a transparent resin because the light emitted isotropically emitted from the blue LED 4 is transmitted, reflected by the reflector on the surface of the cup 10, and emitted above the LED lamp. In particular, when the LED lamp is used as a white light source, the mount 5 may be white so as not to interfere with the white light.

[0046] Further, the mount 5 may contain the phosphor 11. The LED lamp using the phosphor 11 has an extremely high light density as compared with the LED lamp not using the phosphor 11. That is, since the light emitted from the blue LED 4 does not pass through the phosphor 11, the light emitted from the blue LED 4 is reflected by the phosphor 11 provided in the vicinity of the blue LED 4, and is used as light excited by the phosphor 11. It is newly emitted in a direction, reflected by the reflector on the surface of the cup 10, and also reflected by the difference in the refractive index of each part of the LED lamp. Therefore, the light is partially confined in the vicinity of the blue LED 4, the light density in the vicinity of the blue LED 4 becomes extremely high, and the LED lamp emits high brightness.

Since the blue LED 4 emits isotropically and the light is also reflected on the surface of the cup 10, the light is transmitted through the mount 5, so that the light density inside the mount 5 is extremely high. Therefore, when the phosphor 11 is contained in the mount 5, those lights emitted from the blue LED 4 are reflected by the phosphor 11 in the mount 5, and as light excited by the phosphor 11 in the mount 5, etc. It is newly released in the direction. When the phosphor 11 is also contained in the mount 5 in this way, the LED lamp becomes even brighter.

[0048] Further, a resin containing an inorganic material such as Ag in the mount 5 can be used. When the above high-brightness LED lamp is used for a long time, since a resin such as epoxy resin is used for the mount 5 and the internal resin 8, the mount 5 and the internal resin 8 made of synthetic resin near the blue LED 4 poles are used. However, it is colored brown or black and deteriorates, and the luminous efficiency decreases. In particular, the coloring of the mount 5 near the blue LED 4 greatly reduces the luminous efficiency. The mount 5 is required not only to have weather resistance due to the light from the blue LED 4, but also to have adhesiveness and adhesion. For the deterioration of the resin due to this light, a resin containing an inorganic material such as Ag is used for the mount 5. It can be solved by. Such a mount 5 can be easily formed by mixing Ag paste and phosphor 11 with the mount paste, applying it on the metal stem 3 with a mounting device, and adhering the blue LED 4.

[0049] In addition to the Ag-containing epoxy resin, the mount 5 can also use a silicone resin as an organic resin containing an inorganic material. It is necessary that the inorganic material in the mount 5 has good adhesion to the resin and is not deteriorated by the light from the blue LED 4. Therefore, as the inorganic material, one or more of silver, gold, aluminum, copper, alumina, silica, titanium oxide, boron nitride, tin oxide, zinc oxide, and ITO are selected and contained in the resin. In particular, silver, gold, aluminum, copper and the like improve heat dissipation and have conductivity, so that they can be applied to semiconductor devices that are expected to have conductivity. Further, alumina, silica, titanium oxide, boron nitride and the like have strong weather resistance and can maintain high reflectance. The shape of the inorganic material can be various, such as spherical, needle-shaped, or flake-shaped, in consideration of dispersibility, electrical continuity, and the like. The content of the inorganic material in the resin of the mount 5 can be adjusted in various ways such as heat dissipation and electrical conductivity. However, if the content of the inorganic material in the resin is increased, the deterioration of the resin is small, but the adhesion is lowered. Therefore, the content is reduced from 5% by weight or more to 80% by weight or less, and further from 60% by weight to 80% by weight or less. If this is done, the deterioration of the resin can be prevented more optimally.

[0050] By incorporating an inorganic material such as Ag, which is not easily deteriorated by the light emitted by the blue LED 4, in the mount 5 in this way, deterioration of the resin of the mount 5 by light can be suppressed, so that the colored portion due to deterioration can be suppressed. It is possible to prevent a decrease in luminous efficiency and obtain good adhesiveness. Further, the brightness of the LED lamp can be further increased by including the phosphor 11 in the mount 5.

[0051] This makes it possible to provide an LED lamp capable of high-luminance light emission with extremely little decrease in luminous efficiency even when used for a long period of time. Furthermore, by using a material with good thermal conductivity, the characteristics of the blue LED4 can be stabilized and color unevenness can be reduced.

FIG. 2 shows the layer structure of the blue LED 4 of the LED lamp shown in FIG. The blue LED 4 has, for example, a sapphire substrate 41 as a transparent substrate, and on the sapphire substrate 41, for example, as a nitride semiconductor layer by the MOCVD method or the like, for example, a buffer layer 42, an n-type contact layer 43, an n-type clad layer 44, MQW. (multi-quantum well) The active layer 45, the p-type clad layer 46, and the p-type contact layer 47 are sequentially formed, and the translucent electrode 50 is formed on the entire surface of the p-type contact layer 47 by a sputtering method, a vacuum vapor deposition method, or the like. , The p electrode 48 is formed on a part of the translucent electrode 50, and the n electrode 49 is formed on a part of the n-type contact layer 43.

[0053] The buffer layer 42 is made of, for example, AlN, and the n-type contact layer 43 is made of, for example, GaN.

The n-type clad layer 44 is composed of, for example, AlyGa1-yN (0 y &lt;1), and the p-type clad layer 46 is composed of, for example, AlxGa1-xN (0 &lt;x &lt;1), and is a p-type contact. Layer 47 is composed of, for example, AlzGa1-zN (0z &lt;1, z &lt;x). Further, the band gap of the p-type clad layer 46 is made larger than the band gap of the n-type clad layer 44. The n-type clad layer 44 and the p-type clad layer 46 may have a single composition, and the above-mentioned nitride semiconductor films having different compositions and having a thickness of 100 Å or less are laminated so as to have a superlattice structure. It may be configured. By setting the film thickness to 100 Å or less, it is possible to prevent cracks and crystal defects from occurring in the film.

[0055] The MQW active layer 45 is composed of a plurality of well layers made of InGaN and a plurality of barrier layers made of GaN. The thickness of the well layer and the barrier layer is 100 Å or less, preferably 60 to 70 Å so as to form a superlattice layer. Since InGaN has softer crystal properties than other Al-containing nitride semiconductors like AlGaN, by using InGaN as a layer constituting the active layer 45, cracks are generated in the entire laminated nitride semiconductor layer. It becomes difficult to enter. The MQW active layer 45 may be composed of a plurality of well layers made of InGaN and a plurality of barrier layers made of AlGaN. Further, it may be composed of a plurality of well layers made of AlInGaN and a plurality of barrier layers made of AlInGaN. However, the bandgap energy of the barrier layer is made larger than the bandgap energy of the well layer.

[0056] A reflective layer may be formed on the sapphire substrate 41 side of the MQW active layer 45, for example, on the buffer layer 42 side of the n-type contact layer 43. Further, the reflective layer may be formed on the surface opposite to the surface of the sapphire substrate 41 on which the MQW active layer 45 is laminated. The reflective layer preferably has the maximum reflectance with respect to the light emitted from the active layer 45, and may be formed from, for example, Al or a multilayer film of a GaN-based thin film. .. By providing the reflective layer, the light emitted from the active layer 45 can be reflected by the reflective layer, the internal absorption of the emitted light from the active layer 45 can be reduced, and the upward output light can be increased. It is possible to reduce the light incident on the surface and prevent the light deterioration.

[0057] The half-value width of the emission wavelength of the blue LED 4 configured as described above is 50 nm or less, preferably 40 nm or less. The peak emission wavelength of the blue LED 4 is in the range of 380 nm to 500 nm, for example, 450 nm.

[0058] In the LED lamp configured as described above, when a voltage is applied between the lead frames 1 and 2, the blue LED 4 emits blue light having a wavelength of 450 nm. The blue light excites the phosphor 11 in the internal resin 8, and the excited phosphor 11 emits yellow light of 560 to 570 nm. The mixed light of blue light and yellow light in the internal resin 8 passes through the external resin 9 and leaks to the outside, but the mixed light looks white to the human eye, and as a result, The LED lamp appears to emit white light. That is, the phosphor 11 is excited by the blue light emitted by the blue LED 4, has a complementary color relationship with blue, and emits yellow having a wavelength longer than that of blue. In the present invention, a more pure white color can be obtained by combining a plurality of phosphors.

[0059] FIG. 3 shows the configuration of a planar light source device according to a third embodiment of the light emitting device of the present invention, (a) is a plan view, and (b) is an AA line cross section of (a). It is a figure.

[0060] The device for a planar light source shown in FIG. 3 is applied as, for example, a backlight device for a liquid crystal panel, irradiates the liquid crystal panel with light from the back surface side of the liquid crystal panel, and is a non-luminous liquid crystal panel. By giving brightness and contrast to characters and images, the visibility is improved, and it is configured with the following elements.

That is, the device for the planar light source is optically connected to the transparent substantially rectangular light guide plate 70 and the light guide plate 70 by being arranged and embedded in an array on the side surface of the light guide plate 70. A plurality of blue LEDs 4, a light reflection case 71 that surrounds the light emitting surface 70a of the light guide plate 70 and reflects light attached to the light guide plate 70, and faces the light emitting surface 70a of the light guide plate 70. A light diffusion pattern 73 formed by forming a regular and fine uneven pattern on the light reflecting surface 72, and a transparent film 74 having an exit surface 70a covered and attached to a light guide plate 70 and containing a phosphor 11 inside. It is configured with.

[0062] Further, each blue LED 4 is attached to the light reflection case 71 so that a driving voltage of a predetermined voltage is supplied from the power supply via means for power supply such as a bonding wire and a lead frame. The light diffusion pattern 73 diffuses the light emitted from the blue LED 4 inside the light guide plate 70.

[0063] In the planar light source device configured as described above, when a driving voltage is applied to each blue LED 4, light is emitted from each of the driven blue LEDs 4. This emitted light travels in a predetermined direction in the light guide plate 70, hits the light diffusing pattern 73 formed on the reflecting surface 72, is reflected and diffused, passes through the film 74 from the emitting surface 70a, and is emitted as planar emitted light. To. When passing through the film 74, a part of the emitted light of the blue LED 4 is absorbed by the phosphor 11, and at the same time, the wavelength is converted and emitted. As a result, the emission color observed from the front surface of the film 74 becomes a color obtained by synthesizing those lights, for example, white from the above-mentioned principle.

[0064] As described above, according to the device for a planar light source according to the third embodiment, the light emitted from the blue LED 4 is incident on the light guide plate 70, and the incident light is incident on the reflecting surface 72 of the light guide plate 70. The light diffusing pattern 73 formed in the above emits light from the exit surface 70a to the film 74, and in this film 74, a part of the light is absorbed by the phosphor 11 and at the same time the wavelength is converted and emitted. Since it is configured, it is possible to make the emission color white only by the blue LED 4 without using the red, green, and blue LEDs as in the conventional case. Further, since the structure is such that the phosphor 11 and the blue LED 4 do not come into direct contact with each other, deterioration of the phosphor 11 can be suppressed for a long period of time, and a predetermined color tone of the planar light source can be maintained for a long period of time. it can.

[0065] In addition, by changing the type of the phosphor 11 contained in the film 74, it is possible to realize not only white but also other colors of emission. If the film 74 is easily attached and detached and a plurality of types of films 74 containing different types of phosphors 11 are prepared, the color tone of the planar light source can be easily changed by simply replacing the film 74. Can be made to.

[0066] Further, the phosphor 11 is contained in the film 74, and even if it is applied to the surface of the film 74, the same effect as that contained can be obtained.

[0067] Further, the blue LED 4 is optically connected to the light guide plate 70 by being embedded in the light guide plate 70. In addition, the blue LED 4 is adhered to the end surface of the light guide plate 70, or the blue LED 4 emits light. The blue LED 4 and the light guide plate 70 may be optically connected by guiding the blue LED 4 to the end surface of the light guide plate 70 by a light conducting means such as an optical fiber. Also, one blue LED 4 may be used.

FIG. 4 shows an SMD (Surface Mounted Device) type LED lamp according to a fourth embodiment of the light emitting device of the present invention.

[0069] The SMD type LED lamp has the following configuration. A metal frame is formed by two gold pattern wirings 81 and 82 that cover both sides of the insulating glass epoxy resin substrate 80 and are electrically separated from each other, and are made of plastic on the pattern wirings 81 and 82. A frame 83 having the cup 83a of the above is provided. The surface of the cup 83a is a reflector that reflects the emitted light of the blue LED4. The pattern wirings 81 and 82 are asymmetrical, and the upper surface of the pattern wiring 82 is formed up to the center of the bottom of the space formed by the frame body 83, while the other pattern wiring 81 is formed by the frame body 83. It is slightly exposed on the bottom.

[0070] The blue LED 4 is fixed to the upper surface of the pattern wiring 82 by the silver filler-containing epoxy resin paste 84. The p electrode of the blue LED 4 and the pattern wiring 82 are connected by a gold bonding wire 6, and the n electrode of the blue LED 4 and the pattern wiring 81 are connected by a gold bonding wire 7.

The space formed by the cup 83a of the frame body 83 is filled with a sealing agent 88 that becomes transparent after solidification. The blue LED 4 is fixed by the sealant 88. The sealant 88 is mixed with a phosphor 11 containing the above-mentioned divalent europium-activated alkaline earth metal orthosilicate and / or alkaline earth metal orthosilicate as a main component. The sealant 88 is an epoxy resin or a silicone resin.

[0072] The sealant 88 mixed with the fluorescent substance 11 may be filled in the space formed by the cup 83a of the frame body 83, or may be filled up to a portion lowered from the upper edge of the frame body 83. You may be.

[0073] The sealant 88 in which the phosphor 11 is mixed may be further mixed with a diffusing material. Since the diffuser diffusely reflects the light emitted from the blue LED 4 into scattered light, the light from the blue LED 4 can easily hit the phosphor 11 and the amount of light emitted from the phosphor 11 can be increased. The diffusing material is not particularly limited, and a well-known substance can be used.

[0074] In the SMD type LED lamp configured as described above, when a voltage is applied between the pattern wirings 81 and 82, the blue LED 4 emits blue light having a wavelength of 450 nm. The blue light excites the phosphor 11 in the encapsulant 88, and the excited phosphor 11 emits yellow light at 560 to 570 nm. The mixed light of blue light and yellow light in the sealant 88 leaks to the outside, but the mixed light looks white to the human eye, and as a result, the LED lamp becomes white. It looks like it is emitting light. That is, the phosphor 11 is excited by the blue light emitted by the blue LED 4, has a complementary color relationship with blue, and emits yellow having a wavelength longer than that of blue. In the present invention, a more pure white color can be obtained by combining a plurality of phosphors.

[0075] FIG. 5 shows an LED lamp according to a fifth embodiment of the light emitting device of the present invention. In this embodiment, the blue LED 4 can be protected from overvoltage such as static electricity, and the overvoltage protection element 91 is added to the light source having the configuration shown in FIG.

[0076] As shown in FIG. 5, the overvoltage protection element 91 is chipped to the same size as the blue LED 4, and is arranged between the blue LED 4 and the mount 5. In the present embodiment, unlike the case of FIG. 1, the blue LED 4 is mounted on a flip chip for the reason described later. The overvoltage protection element 91 includes electrodes 92 and 93 for connecting to the blue LED 4 and the lead frame 1. The electrode 92 is provided at a position facing the p electrode 48 shown in FIG. Further, the electrode 93 is provided at a position facing the n electrode 49, and is formed so as to extend to the side surface of the overvoltage protection element 91 in order to facilitate connection with the bonding wire 6. The electrodes 92 and 93 on the overvoltage protection element 91 are connected to the p electrode 48 and the n electrode 49 of the blue LED 4 via Au bumps 94a and 94b, respectively. As the overvoltage protection element 91, a zener diode that is energized when a voltage equal to or higher than a specified voltage is applied, a capacitor that absorbs a pulsed voltage, or the like can be used.

FIG. 6 shows a connection circuit when a Zener diode is used for the overvoltage protection element 91. The Zener diode 95 as the overvoltage protection element 91 is electrically connected in parallel to the blue LED4, the anode of the blue LED4 and the cathode of the Zener diode 95 are connected, and the cathode of the blue LED4 and the Zener diode 95 are connected. The anode is connected. When an excessive voltage is applied between the lead frame 1 and the lead frame 2, when the voltage exceeds the Zener voltage of the Zener diode 95, the voltage between the terminals of the blue LED 4 is held at the Zener voltage and exceeds this Zener voltage. It will never be. Therefore, it is possible to prevent an excessive voltage from being applied to the blue LED 4, protect the blue LED 4 from the excessive voltage, and prevent element destruction and performance deterioration.

FIG. 7 shows a connection circuit when a capacitor is used for the overvoltage protection element 91. As the capacitor 96 as the overvoltage protection element 91, a chip type component for surface mounting can be used. The capacitor 96 having such a structure is provided with strip-shaped electrodes on both sides, and these electrodes are connected in parallel to the anode and cathode of the blue LED4. When an excessive voltage is applied between the lead frame 1 and the lead frame 2, the charging current flows through the capacitor 96 due to this excessive voltage, the voltage between the terminals of the capacitor 96 is instantly lowered, and the applied voltage for the blue LED 4 does not rise. Therefore, the blue LED 4 can be protected from overvoltage. Also, when noise containing high frequency components is applied, the capacitor 96 functions as a bypass capacitor, so that external noise can be eliminated.

[0079] As described above, the blue LED4 is flip-chip mounted upside down with respect to FIG. The reason is that since the overvoltage protection element 91 is provided, both the overvoltage protection element 91 and the blue LED 4 need to be electrically connected. If each of the blue LED 4 and the overvoltage protection element 91 is connected by a bonding wire, the number of bonds increases, which reduces productivity, and the number of contacts and disconnections between the bonding wires increases, resulting in a decrease in reliability. May lead to. Therefore, the blue LED4 is mounted on a flip chip. That is, the lower surface of the sapphire substrate 41 shown in FIG. 2 is the uppermost surface, the p electrode 48 is connected to the electrode 92 of the overvoltage protection element 91 via the Au bump 94a, and the n electrode 49 is overvoltageed via the Au bump 94b. It is connected to the electrode 93 of the protection element 91 so that the bonding wires 6 and 7 do not have to be connected to the blue LED 4. When the blue LED 4 is a flip chip, the translucent electrode 50 shown in FIG. 2 can be replaced with a non-translucent electrode. Further, the n-electrode 49 may be thickened so as to be flush with the surface of the p-electrode 48, or a conductor may be newly connected to the n-electrode 42 and used as an electrode.

As described above, according to the configuration of FIG. 5, in addition to the basic effect as a light source by the configuration shown in FIG. 1, the overvoltage protection element 91 is provided, so that the overvoltage due to static electricity or the like is provided. Will not damage the blue LED4 or cause performance degradation even if is applied. Further, since the overvoltage protection element 91 functions as a submount, even if the blue LED4 is flip-chip mounted, the height of the bonding position on the chip side of the bonding wires 6 and 7 does not decrease. Bonding can be performed at almost the same height position as in the case of.

[0081] In FIGS. 5 and 6, when a semiconductor element is used for the overvoltage protection element 91, a general silicon diode may be used instead of the Zener diode 95. In this case, multiple silicon diodes are connected in series with the same polarity, and the number of silicon diodes used is determined so that the total value of the forward voltage drop (about 0.7 V number) is equivalent to the operating voltage with respect to the overvoltage. To do.

[0082] Further, a variable resistor element can be used for the overvoltage protection element 91. This variable resistance element has a characteristic that the resistance value decreases as the applied voltage increases, and overvoltage can be suppressed in the same manner as the Zener diode 95.

FIG. 8 shows a semiconductor light emitting device according to a sixth embodiment of the light emitting device of the present invention.

The semiconductor light emitting device shown in FIG. 8 converts the light emitted from the light emitting element into wavelength and radiates it to the outside of the lens-type resin encapsulant, and the lead shown in FIG. 1 described above. Others include frames 1, 2, metal stem 3, blue LED 4, mount 5, bonding wires 6, 7, internal resin 8 that does not contain phosphor 11, external resin 9, and cup 10. In addition, a translucent fluorescent cover 100 that is in close contact with and surrounds the outer surface of the external resin 9 and contains the phosphor 11 is provided.

[0085] The fluorescent cover 100 is formed by containing, for example, a phosphor 11 that is excited by the light emission of the blue LED 4 and emits fluorescence in a resin base material. The resin base material is, for example, a translucent polyester resin, an acrylic resin, a urethane, a nylon, a silicone resin, a vinyl chloride, a policerol, a bakelite, a CR39 (acrylic glycol carbonate resin), or the like, and is a urethane, nylon, or silicone resin. Gives the fluorescent cover 100 a certain degree of elasticity, so that it can be easily attached to the external resin 9.

[0086] Further, the fluorescent cover 100 has a shape that is in close contact with the outer surface of the external resin 9, that is, a shape in which a hemispherical cover is integrally formed on the upper portion of the cylindrical cover, and is detachably attached to the external resin 9. It is attached. Further, the fluorescent cover 100 is preferably in the form of a thin film in order to reduce light scattering by the phosphor 11. Further, the fluorescent cover 100 can be completed relatively easily by forming a predetermined shape by injection molding of a resin containing the phosphor 11 and then adhering to the external resin 9, but between the external resin 9 and the fluorescent cover 100. In order to prevent the formation of an air layer in the plastic, the resin raw material containing the phosphor 11 may be directly sprayed onto the external resin 9 and then cured to form the fluorescent cover 100.

[0087] In the semiconductor light emitting device configured as described above, the light emitted from the blue LED 4 is incident on the fluorescence cover 100 via the internal resin 8 and the external resin 9. A part of this incident light is absorbed by the phosphor 11, and at the same time, the wavelength is converted and emitted to the outside. As a result, the emission color observed from the outer surface of the fluorescence cover 100 becomes a color obtained by synthesizing those lights, for example, white from the above-mentioned principle.

[0088] As described above, according to the semiconductor light emitting device of the sixth embodiment, the inner resin 8 and the outer resin 9 which are the resin encapsulants of the blue LED 4 do not contain the phosphor 11 and the outer resin 9 is used. Since the fluorescent substance 11 is contained in the fluorescent cover 100 that covers the outer surface, light scattering by the fluorescent substance 11 does not occur in the internal resin 8 and the external resin 9. Further, since the fluorescent cover 100 forms a thin film, light scattering by the phosphor 11 is relatively small. Therefore, by making the shape of the lens portion of the external resin 9 an arbitrary shape (hemispherical in the above embodiment), desired light directivity can be obtained, and a decrease in brightness due to wavelength conversion can be minimized. Can be done.

[0089] In addition, by changing the type of the phosphor 11 contained in the base material of the fluorescent cover 100, it is possible to realize not only white but also other colors of emission. If the mounting structure of the fluorescent cover 100 is made easy to attach / detach and a plurality of types of fluorescent covers 100 containing different types of phosphors 11 are prepared, the color tone of the emitted light can be easily adjusted by simply replacing the fluorescent cover 100. Can be changed.

[0090] Further, the phosphor 11 is contained in the fluorescent cover 100, and even if it is applied to the surface of the fluorescent cover 100, the same effect as that contained can be obtained. Further, since the fluorescence cover 100 can be attached to a commercially available semiconductor light emitting element, the semiconductor light emitting device can be manufactured at low cost.

[Effect of the Invention]<u style="single">According to the present invention</u>It was surprisingly found that the wavelength of emitted light was longer when strontium silicate or a mixture of barium silicate and strontium orthosilicate silicate was used instead of barium silicate. Germanium substitution of silicon part as well as additional P₂O_{<u style="single">5</u>}, Al₂O₃And / or B₂O₃Also has an effect on the emission spectrum, so that the emission spectrum can be optimally adjusted for each use case.

Advantageously, the light emitting device is another phosphor and / or Y (V, P, Si) from the group of alkaline earth metal aluminates activated with divalent europium and / or manganese. ) O₄: Eu or Equation: Me (3-xy) MgSi₂O₃Alkaline earth metal-magnesium-disilicate: Eu, represented by: xEu, yMn (in the formula, 0.005 &lt;x &lt;0.5, 0.005 &lt;y &lt;0.5, Me stands for Ba and / or Sr and / or Ca)²⁺, Mn²⁺It has yet another red-emitting phosphor from the group of.

[0093] Furthermore, it has been found that the incorporation of small amounts of monovalent ions, especially halides, into the fluorophore lattice is advantageous for crystallinity and emissivity.

[0094] It is advantageous if the first spectral region is 300 to 500 nm. In this wavelength region, the fluorophore according to the present invention can be well excited.

[0095] Further, it is advantageous when the second spectral region is from 430 nm to 650 nm. In this case, a relatively pure white color is obtained.

Advantageously, the light emitting device emits white light having a Ra value> 72.

[0097] As described above, the light emitting device having the light emitting element and the phosphor according to the present invention is suitable for LED displays, backlight devices, traffic lights, illuminated switches, various sensors, and various indicators.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of an LED lamp according to a second embodiment of the light emitting device of the present invention.

FIG. 2 is a cross-sectional view showing a layer structure of the blue LED shown in FIG.

3A and 3B show a configuration of a planar light source device according to a third embodiment of the light emitting device of the present invention, where FIG. 3A is a plan view and FIG. 3B is a sectional view taken along line AA of FIG. 3A.

FIG. 4 is a cross-sectional view of an SMD (Surface Mounted Device) type LED lamp according to a fourth embodiment of the light emitting device of the present invention.

FIG. 5 is a cross-sectional view of an LED lamp according to a fifth embodiment of the light emitting device of the present invention.

FIG. 6 is a connection circuit diagram when a Zener diode is used as an overvoltage protection element.

FIG. 7 is a connection circuit diagram when a capacitor is used as an overvoltage protection element.

FIG. 8 is a cross-sectional view of a semiconductor light emitting device according to a sixth embodiment of the light emitting device of the present invention.

[Explanation of symbols]<u style="single">1</u><u style="single">Lead frame</u><u style="single">2</u><u style="single">Lead frame</u><u style="single">3</u><u style="single">Metal stem</u><u style="single">4</u><u style="single">Blue LED</u><u style="single">5</u><u style="single">mount</u><u style="single">6</u><u style="single">Bonding wire</u><u style="single">7</u><u style="single">Bonding wire</u><u style="single">8</u><u style="single">Internal resin</u><u style="single">9</u><u style="single">External resin</u><u style="single">10</u><u style="single">cup</u><u style="single">11</u><u style="single">Fluorescent material</u><u style="single">41</u><u style="single">Sapphire substrate</u><u style="single">42</u><u style="single">Buffer layer</u><u style="single">43</u><u style="single">n-type contact layer</u><u style="single">44</u><u style="single">n-type clad layer</u><u style="single">45</u><u style="single">MQW active layer</u><u style="single">46</u><u style="single">p-type clad layer</u><u style="single">47</u><u style="single">p-type contact layer</u><u style="single">48</u><u style="single">p electrode</u><u style="single">49</u><u style="single">n electrode</u><u style="single">50</u><u style="single">Translucent electrode</u><u style="single">70</u><u style="single">Light guide plate</u><u style="single">70a</u><u style="single">Exit surface</u><u style="single">71</u><u style="single">Light reflective case</u><u style="single">72</u><u style="single">Reflective surface</u><u style="single">73</u><u style="single">Light diffusion pattern</u><u style="single">74</u><u style="single">the film</u><u style="single">81</u><u style="single">Pattern wiring</u><u style="single">82</u><u style="single">Pattern wiring</u><u style="single">83</u><u style="single">Frame</u><u style="single">83a</u><u style="single">cup</u><u style="single">88</u><u style="single">Encapsulant</u><u style="single">91</u><u style="single">Overvoltage protection element</u><u style="single">92</u><u style="single">electrode</u><u style="single">93</u><u style="single">electrode</u><u style="single">94a</u><u style="single">Au bump</u><u style="single">94b</u><u style="single">Au bump</u><u style="single">95</u><u style="single">Zener diode</u><u style="single">96</u><u style="single">Capacitor</u><u style="single">100</u><u style="single">Fluorescent cover</u>