JP2011023560A - Light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting device capable of improving wavelength conversion efficiency of a wavelength conversion portion. <P>SOLUTION: The light emitting device includes an LED chip 1, and the wavelength conversion portion 2 disposed on a light extraction surface side of the LED chip 1 to convert part of light emitted from the LED chip 1 into light having a wavelength longer than that of the LED chip 1. The wavelength conversion portion 2 is composed of a structure wherein a plurality of wavelength conversion element portions 21 are combined and arrayed, which use fluorescent glass as glass to which a rare earth element excited with the light emitted from the LED chip 1 to emit the light having the wavelength longer than that of the LED chip 1 is added. In the wavelength conversion portion 2, the wavelength conversion element portions 21 are optical fibers 120 each including the fluorescent glass as a core 121, and the respective optical fibers 120 are arrayed each having an optical-axis direction aligned with the optical axis direction of the LED chip 1. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a light emitting device using an LED chip.

  Conventionally, an LED chip and a glass phosphor layer that is a wavelength conversion unit that is formed on the light extraction surface of the LED chip and converts part of the light emitted from the LED chip into light having a longer wavelength than the LED chip. There has been proposed a light emitting device that includes a desired color mixture light (for example, white light) (see, for example, Patent Document 1). In the light emitting device disclosed in Patent Document 1, since the mold part that covers the laminated body of the LED chip and the glass phosphor layer, a part of each lead, and the like is formed in a bullet-shaped shape, the mold part The directivity can be strengthened by the lens effect.

JP 2002-33521 A

  By the way, in the light emitting device disclosed in Patent Document 1, the wavelength conversion is performed by the glass phosphor layer formed on the light extraction surface of the LED chip, but the wavelength conversion efficiency of the glass phosphor layer is low, and the wavelength Improvement of conversion efficiency is desired. In particular, when a light emitting device using an LED chip is used as a light source incorporated in a lighting fixture, a larger light output is required. However, increasing the chip size of the LED chip is a light distribution lens such as a hybrid lens. Since the light distribution controllability of the light distribution control member such as a reflecting mirror is deteriorated, it is desired to improve the wavelength conversion efficiency in the wavelength conversion unit.

  This invention is made | formed in view of the said reason, The objective is to provide the light-emitting device which can aim at the improvement of the wavelength conversion efficiency of a wavelength conversion part.

  The invention of claim 1 includes an LED chip and a wavelength conversion unit that is disposed on the light extraction surface side of the LED chip and converts part of the light emitted from the LED chip into light having a longer wavelength than the LED chip. The wavelength conversion unit is a combination of a plurality of wavelength conversion element units using fluorescent glass that is excited by light emitted from the LED chip and added with a rare earth element that emits light having a longer wavelength than the LED chip. It consists of an arrayed structure.

  According to this invention, the wavelength conversion unit disposed on the light extraction surface side of the LED chip is added with a rare earth element that is excited by light emitted from the LED chip and emits light having a longer wavelength than the LED chip. Since it consists of a structure in which multiple wavelength conversion elements using fluorescent glass, which is glass, are combined and arranged, the optical path length in the wavelength converter of the light emitted from the LED chip can be increased, and the wavelength The wavelength conversion efficiency of the conversion unit can be improved.

  According to a second aspect of the present invention, in the first aspect of the invention, the wavelength conversion unit is an optical fiber in which the wavelength conversion element unit has the fluorescent glass as a core, and an optical axis direction of each optical fiber is the LED chip. It is characterized by being arranged so as to coincide with the optical axis direction.

  According to this invention, the wavelength conversion element part of the wavelength conversion part is an optical fiber, and the optical axis direction of each optical fiber is arranged in a form that matches the optical axis direction of the LED chip. Propagation of light can be suppressed, and directivity can be enhanced.

  According to a third aspect of the present invention, in the first aspect of the invention, the wavelength conversion unit is a bead made of the fluorescent glass, and the wavelength conversion element unit is arranged so as to have a three-dimensional periodic structure. And

  According to this invention, since the wavelength conversion element part of the wavelength conversion part is a bead and is arranged so as to have a three-dimensional periodic structure, the light radiated from the LED chip is multiplexed and reflected in the wavelength conversion part. Therefore, it becomes easier to confine, and the wavelength conversion efficiency of the wavelength conversion unit can be increased.

  According to a fourth aspect of the present invention, in the first aspect of the present invention, the wavelength conversion section includes a plurality of the wavelength conversion element sections formed in a sheet shape using the fluorescent glass and at least on the side opposite to the LED chip side. It is a sheet-like member in which minute convex portions are formed, and is arranged so as to overlap in the optical axis direction of the LED chip.

  According to this invention, the wavelength conversion part is formed in a sheet shape with the wavelength conversion element part using the fluorescent glass, and a plurality of minute convex parts are formed at least on the side opposite to the LED chip side. Sheet-like members, which are arranged so as to overlap in the optical axis direction of the LED chip, so that the light emitted from the LED chip can be easily confined by multiple reflection in the wavelength conversion unit, and the wavelength conversion of the wavelength conversion unit Efficiency can be increased.

  According to a fifth aspect of the present invention, in the first to fourth aspects of the present invention, the wavelength conversion unit is enclosed in a plane orthogonal to the optical axis direction of the LED chip and light from each of the LED chip and the rare earth element is reflected. A photonic crystal is provided.

  According to this invention, by providing a photonic crystal that surrounds the wavelength conversion unit in a plane orthogonal to the optical axis direction of the LED chip and reflects light from each of the LED chip and the rare earth element, Directivity can be strengthened.

  In the invention of claim 1, there is an effect that the wavelength conversion efficiency of the wavelength conversion section can be improved.

The light-emitting device of Embodiment 1 is shown, (a) is a schematic side view, (b) is a schematic exploded perspective view. It is explanatory drawing of the wavelength conversion part of the other structural example of a light-emitting device same as the above. The light-emitting device of Embodiment 2 is shown, (a) is a schematic side view, (b) is a schematic exploded perspective view. The light-emitting device of Embodiment 3 is shown, (a) is a schematic side view, (b) is a schematic exploded perspective view. The light-emitting device of Embodiment 4 is shown, (a) is a schematic sectional drawing, (b) is a schematic exploded perspective view.

(Embodiment 1)
As shown in FIG. 1, the light emitting device according to the present embodiment has an LED chip 1 and a part of light emitted from the LED chip 1 disposed on the light extraction surface side of the LED chip 1 longer than the LED chip 1. And a wavelength converter 2 for converting the light into a wavelength.

  The above-described LED chip 1 is a GaN-based blue LED chip that emits blue light, and each electrode (anode electrode, cathode electrode) (not shown) is formed on one surface side in the thickness direction. Flip chip mounting is used on a mounting board (not shown). The LED chip 1 is not limited to the blue LED chip. For example, a purple LED chip that emits purple light, an ultraviolet LED chip that emits ultraviolet light, a green LED chip that emits green light, and the like. But you can. In this embodiment, the LED chip 1 having a chip size of 1 mm □ is used, but the chip size of the LED chip 1 is not particularly limited. The LED chip 1 has each electrode formed on the one surface side in the thickness direction, but one electrode is formed on the one surface side in the thickness direction, and the other electrode is formed on the other surface side. What is used may be used, and the mounting structure when mounted on the mounting board is not particularly limited.

  The wavelength conversion unit 2 is a plurality of wavelength conversion element units 21 using fluorescent glass that is excited by light emitted from the LED chip 1 and added with a rare earth element that emits light having a longer wavelength than the LED chip 1. Are constituted by structures arranged in combination.

  Here, in the light emitting device of the present embodiment, the wavelength conversion element unit 21 of the wavelength conversion unit 2 is the optical fiber 120 having the above-described fluorescent glass as the core 121, and the optical axis direction of each optical fiber 120 is the LED chip 1. They are arranged so as to coincide with the optical axis direction. In short, the wavelength conversion unit 2 includes a plurality of rare earth elements that are excited by light emitted from the LED chip 1 and emit light having a longer wavelength than the LED chip 1 and are optically coupled to the LED chip 1. The linear optical fiber 120 is provided.

  In the optical fiber 120, the rare earth element is added to the core 121 as described above. When the emission color of the LED chip 1 is blue as described above, the rare earth element may be, for example, Pr (green to red light). Sm (emits orange to red light), Eu (emits red light), Er (emits green to red light), Ho (emits green to red light) , Dy (emits yellow light), Tb (emits green light), and the like.

  The optical fiber 120 employs a single mode fiber, but is not limited to a single mode fiber, but a step index type (SI type) multimode fiber, a graded index type (GI type) multimode fiber, or the like. It may be adopted. Further, the optical fiber 120 may include only the core 121 (air is clad).

  By the way, the optical fiber 120 is arranged on the light extraction surface side of the LED chip 1 so that the optical axis direction of the optical fiber 120 coincides with the optical axis direction of the LED chip 1 (a parallel shape) as described above. In addition, it is formed in such a length that amplified spontaneous emission (Amplified Spontaneous Emission) is emitted from an end surface (light emitting surface) opposite to the LED chip 1 side. The length of the optical fiber 120 depends on the diameter of the core 121, but when the diameter of the core 121 is 0.05 mm (50 μm), for example, the total length of the core 121 (distance between both end faces) is 4 mm. What is necessary is just to set suitably so that it may become in the range of about 10 mm.

  In the light emitting device of the present embodiment described above, the wavelength conversion unit 2 uses fluorescent glass to which a rare earth element that is excited by light emitted from the LED chip 1 and emits light having a longer wavelength than the LED chip 1 is added. Since the plurality of wavelength conversion element portions 21 are combined and arranged, the optical path length of the light emitted from the LED chip 1 in the wavelength conversion portion 2 can be increased. The wavelength conversion efficiency can be improved.

  Further, in the light emitting device of the present embodiment, the wavelength conversion element unit 21 of the wavelength conversion unit 2 is the optical fiber 120 having the above-described fluorescent glass as the core 121, and the optical axis direction of each optical fiber 120 is the light of the LED chip 1. Since they are arranged so as to coincide with the axial direction, the propagation of light in the lateral direction can be suppressed and the directivity can be enhanced. Since the light emitting device of the present embodiment has high directivity, the light distribution control by a light distribution control member such as a lens or a reflector is highly flexible, and the light output is large. It can also be applied as a light source for lighting fixtures, etc., or a light source for automobile headlights.

  Here, in the light emitting device of the present embodiment, by appropriately selecting the rare earth element of the fluorescent glass, the light from the LED chip 1 and the rare earth element can be obtained from the end surface of the optical fiber 120 opposite to the LED chip 1 side. White light can be radiated as light mixture.

  By the way, in the light emitting device of the present embodiment, if the wavelength conversion unit 2 is configured by a structure in which a plurality of types of wavelength conversion element units 21 having different conversion wavelengths are combined, a wavelength used for the structure. The light emission color can be adjusted by the combination of the conversion element portions 21, color variation can be reduced, and white light with high color rendering can be obtained.

Here, for example, when combining seven types of wavelength conversion element portions 21 having different conversion wavelengths, the respective conversion wavelengths are changed to λ ₁ , λ ₂ , λ ₃ , λ ₄ , λ ₅ , λ ₆ , λ ₇ , λ _8. As shown in FIG. 2 (a), the wavelength conversion element unit 21 is placed at the center of the wavelength conversion element unit 21 at each lattice point of the virtual triangular lattice in the plane orthogonal to the optical axis direction of the LED chip 1. A plurality of wavelength conversion element parts 21 may be arranged in a two-dimensional array so that the wavelength conversions coincide with each other, and the wavelength conversion elements 21 adjacent to each other may have different conversion wavelengths. Similarly, when four types of wavelength conversion element units 21 having different conversion wavelengths are combined, assuming that the respective conversion wavelengths are λ ₁ , λ ₂ , λ ₃ , and λ ₄ , the wavelength conversion element unit 21 is shown in FIG. ).

(Embodiment 2)
The basic configuration of the light emitting device of this embodiment is substantially the same as that of the first embodiment, and the structure of the wavelength converter 2 is different as shown in FIG. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted.

  In the wavelength conversion unit 2 in this embodiment, the wavelength conversion element unit 21 is a bead 321 made of fluorescent glass, and is arranged so as to have a three-dimensional periodic structure. In the present embodiment, the bead 321 has a hemispherical shape in order to enhance the stability when the beads 321 are arranged. However, the shape of the bead 321 is not limited to a hemispherical shape, and the non-converted light from the rare earth element is not confined. It may be a true spherical shape, and may be, for example, a semi-elliptical sphere or an elliptic sphere. Further, the shape of the beads 321 is elliptical, and the bead 321 is arranged so that the direction along the optical axis direction of the LED chip 1 is the major axis direction. If the major axis is increased, the length in the longitudinal direction (major axis direction) is increased. It is also possible to obtain amplified spontaneous emission light. Note that the size of the beads 321 may be set to about several μm.

  Therefore, in the light emitting device of the present embodiment, the wavelength conversion element portion 21 of the wavelength conversion portion 2 is the beads 321 made of fluorescent glass, and is arranged so as to have a three-dimensional periodic structure. Propagation can be suppressed, and directivity can be enhanced.

(Embodiment 3)
The basic configuration of the light emitting device of this embodiment is substantially the same as that of the first embodiment, and the structure of the wavelength converter 2 is different as shown in FIG. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted.

  In the wavelength conversion unit 2 according to the present embodiment, the wavelength conversion element unit 21 is formed in a sheet shape using fluorescent glass, and has a large number of convex portions 322 on the side opposite to the LED chip 1 side and on the LED chip 1 side. 323 is a sheet-like member 321 in which a plurality of sheet-like members 321 are arranged so as to overlap in the optical axis direction of the LED chip 1. In short, each sheet-like member 321 is arranged in a form in which the thickness direction of each sheet-like member 321 coincides with the optical axis direction of the LED chip 1. The optical axis direction of the LED chip 1 coincides with the thickness direction of the LED chip 1.

  The convex part 322 on the opposite side to the LED chip 1 side in the sheet-like member 321 and the convex part 323 on the LED chip 1 side are arranged so as to correspond one-to-one.

  In the light emitting device of the present embodiment described above, the wavelength conversion unit 2 is arranged such that the above-described sheet-like member 321 that is the wavelength conversion element unit 21 is overlapped in the optical axis direction of the LED chip 1. The emitted light is easily confined by the multiple reflection in the wavelength conversion unit 2, and the wavelength conversion efficiency of the wavelength conversion unit 2 can be increased. Here, the sheet-like member 321 in the present embodiment has a plurality of convex portions 322 and 323 formed on the side opposite to the LED chip 1 side and on the LED chip 1 side, but at least with the LED chip 1 side. The convex part 322 should just be formed in the other side. Here, the convex portion 322 on the opposite side to the LED chip 1 side in the sheet-like member 321 is preferably formed in a plano-convex lens shape in order to enhance the directivity of the converted light, and the LED in the sheet-like member 321 The convex portion 323 on the chip 1 side is preferably formed in a plano-convex lens shape in order to suppress the divergence of light emitted from the LED chip 1. Note that the microstructure formed by the pair of convex portions 322 and 323 and the portion between the convex portions 322 and 323 that overlap in the thickness direction of the sheet-like member 321 is confined by the light converted by the rare earth element. For example, the shape may be a non-spherical shape, for example, may be an elliptical shape, and if the direction along the optical axis direction of the LED chip 1 is the longer diameter direction and the longer diameter is increased, the longer direction It is also possible to obtain amplified spontaneous emission light (in the major axis direction). Further, in this embodiment, a number of microstructures constituted by a pair of convex portions 322 and 323 that overlap in the thickness direction of the sheet-like member 321 and portions between both convex portions 322 and 323 are converted into wavelengths. Since the entire portion 2 is arranged so as to have a fine structure, the wavelength conversion of the wavelength conversion portion 2 is compared with the case where the structures in which the microstructures are arranged in a straight line in the thickness direction of the LED chip 1 are arranged in parallel. Efficiency can be further increased. Here, the both convex portions 322 and 323 at both ends in the horizontal direction may have a vertically-divided shape (half body).

  In the light emitting device of this embodiment, since the wavelength conversion element 21 of the wavelength conversion unit 2 is the above-mentioned sheet-like member 321, a plurality of types of sheet-like members 321 having different conversion wavelengths are prepared and appropriately stacked. By arranging, the emission color can be easily adjusted.

(Embodiment 4)
The basic configuration of the light emitting device of the present embodiment is substantially the same as that of the second embodiment. As shown in FIG. 5, the wavelength conversion unit 2 is enclosed in a plane orthogonal to the optical axis direction of the LED chip 1, and the LED chip 1 and the wavelength. The only difference is that a photonic crystal 4 that reflects light from each of the rare earth elements of the converter 2 is provided. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 2, and description is abbreviate | omitted.

  In the photonic crystal 4 described above, the fine spheres 42 made of the first material are three-dimensionally arranged at a predetermined period, and a second material having a refractive index different from that of the first material is provided between the adjacent spheres 42. Although it is a three-dimensional photonic crystal having a filled artificial opal structure, the structure of the photonic crystal 4 is not particularly limited. For example, an inverted opal structure may be adopted. The photonic crystal 4 is not limited to a three-dimensional photonic crystal, and may be a two-dimensional photonic crystal or a one-dimensional photonic crystal.

  Thus, in the light emitting device of the present embodiment, the photonic crystal 4 is provided that surrounds the wavelength conversion unit 2 in a plane orthogonal to the optical axis direction of the LED chip 1 and reflects light from each of the LED chip 1 and the rare earth element. As a result, the directivity can be enhanced, and the light emitted from the LED chip 1 can be incident on the wavelength converter 2 more efficiently.

DESCRIPTION OF SYMBOLS 1 LED chip 2 Wavelength conversion part 4 Photonic crystal 21 Wavelength conversion element part 120 Optical fiber 121 Core 122 Cladding 221 Bead 321 Sheet-like member 322 Convex part 323 Convex part

Claims (5)

  The LED chip and a wavelength conversion unit that is disposed on the light extraction surface side of the LED chip and converts a part of the light emitted from the LED chip into light having a longer wavelength than the LED chip. It consists of a structure in which a plurality of wavelength conversion elements using fluorescent glass, which is a glass doped with rare earth elements that are excited by light emitted from the chip and emit light having a longer wavelength than the LED chip, are arranged in combination. A light emitting device characterized by that.   The wavelength conversion unit is configured such that the wavelength conversion element unit is an optical fiber having the fluorescent glass as a core, and an optical axis direction of each optical fiber is aligned with an optical axis direction of the LED chip. The light-emitting device according to claim 1.   The light emitting device according to claim 1, wherein the wavelength conversion unit is configured such that the wavelength conversion element unit is a bead made of the fluorescent glass and has a three-dimensional periodic structure.   The wavelength conversion part is a sheet-like member in which the wavelength conversion element part is formed in a sheet shape using the fluorescent glass, and at least a plurality of minute convex parts are formed on the side opposite to the LED chip side. The light-emitting device according to claim 1, wherein the light-emitting devices are arranged so as to overlap in an optical axis direction of the LED chips.   The photonic crystal which surrounds the said wavelength conversion part within the surface orthogonal to the optical axis direction of the said LED chip, and reflects the light from each of the said LED chip and the said rare earth elements is provided. The light emitting device according to claim 4.

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