JP2010183035A - Light-emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting device capable of reducing color variations radiated from the device in the light-emitting device whose lens part is a dome type. <P>SOLUTION: The light-emitting device 1 includes a light-emitting element 3 that is directly or indirectly mounted on a substrate 2, a fluorescent layer 4 having a side face coating portion 43 coating a side face 31 of the light-emitting element 3 and an upper face coating portion 44 which is formed thicker than the side surface coating portion 43 and coating an upper face 32 of the light-emitting element 3, and a dome-type lens portion 5 covering the light-emitting element 3 coated by the fluorescent layer 4 on the substrate 2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a light emitting device including a light emitting element mounted on a substrate, a fluorescent layer that covers the light emitting element, and a dome-shaped lens portion that covers the light emitting element covered with the fluorescent layer.

  As a light emitting device of this type, a light emitting element is mounted on the upper surface of a pedestal having a lead electrode, and covers the upper surface and side surfaces of the light emitting element and the outer peripheral surface of the first resin mixed with a fluorescent material. A dome-shaped second resin is known (for example, see Patent Document 1). In this light emitting device, the second resin forms a lens portion, and the first resin forms a fluorescent layer. In Patent Document 1, the film thickness of the first resin is constant on the upper surface and side surfaces.

JP 2005-268431 A

  However, when the lens portion is a dome shape, there is a problem that uneven color of light emitted from the device increases if the fluorescent layer has the same film thickness on the upper surface and side surfaces of the light emitting element.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a light-emitting device capable of reducing uneven color of light emitted from the device in a dome-type light-emitting device. There is to do.

  According to the present invention, the light emitting element mounted directly or indirectly on the substrate, the side surface covering portion that covers the side surface of the light emitting element, and the upper surface of the light emitting element that is formed thicker than the side surface covering portion. There is provided a light emitting device comprising: a fluorescent layer having an upper surface covering portion to cover; and a dome-shaped lens portion that covers the light emitting element covered with the fluorescent layer on the substrate.

  In the light emitting device, the phosphor layer includes phosphor particles and a transparent material in which the phosphor particles are dispersed, and the refractive index of the lens unit is the same as the refractive index of the transparent material of the phosphor layer. Or it is preferable that it is large.

  In the above light emitting device, it is preferable that the lens portion is formed of the same material as the transparent material of the fluorescent layer.

  ADVANTAGE OF THE INVENTION According to this invention, in the dome-type light-emitting device with a lens part, the color nonuniformity of the light radiated | emitted from an apparatus can be reduced.

FIG. 1 is a cross-sectional explanatory view of a light emitting device showing an embodiment of the present invention. FIG. 2 is a cross-sectional explanatory view of a light emitting device showing Comparative Example 1. FIG. 3 is a graph showing the relationship between the angle with respect to the optical axis (axis perpendicular to the center of the upper surface of the LED element) and chromaticity of the light emitted outside the apparatus of Example and Comparative Example 1. FIG. 4 is a cross-sectional explanatory view of a light emitting device showing a comparative example 2. FIG. 5 is a graph showing the relationship between the angle with respect to the optical axis and the relative chromaticity of the light emitted to the outside of the devices of Comparative Example 1 and Comparative Example 2.

FIG. 1 shows an embodiment of the present invention, and FIG. 1 is an external perspective view of a light emitting device.
As shown in FIG. 1, the light emitting device 1 includes an LED element 3 that is directly mounted on a substrate 2, a fluorescent layer 4 that entirely covers the LED element 3, and a fluorescent layer 4 on the substrate 2. And a lens portion 5 that covers the covered LED element 3. In the present embodiment, blue light is emitted from the LED element 3, and part of the blue light is converted into yellow light by the fluorescent layer 4, whereby white light is emitted from the lens unit 5 to the outside of the apparatus. .

  The board | substrate 2 is formed in flat form, for example, consists of ceramics, such as CuW and an alumina. On the upper surface of the substrate 2, a circuit pattern (not shown) that is electrically connected to the LED element 3 is formed. In addition, the board | substrate 2 is not limited to a ceramic, For example, you may form with resin materials like glass epoxy.

The LED element 3 is a flip chip type, and is connected to the circuit pattern of the ceramic substrate 2 by a bump (not shown). The LED element 3 is, for example, a GaN-based semiconductor represented by a formula of In _x Al _y Ga _1-xy N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1) on a sapphire substrate. Is formed.

  The fluorescent layer 4 contains phosphor particles 41 that emit light emitted from the LED element 3 as excitation light and emit wavelength-converted light having a longer wavelength than the excitation light. As the phosphor particles 41, for example, an aluminate phosphor such as a YAG (yttrium aluminum garnet) phosphor, for example, a silicate phosphor such as a BOS (barium ortho-silicate) phosphor is used. Can do. The fluorescent layer 4 includes a transparent material 42 in which the phosphor particles 41 are dispersed. As the transparent material 42, for example, an epoxy resin, a silicone resin, or the like can be used.

  The fluorescent layer 4 includes a side surface covering portion 43 that covers the side surface 31 of the LED element 3 and an upper surface covering portion 44 that is formed thicker than the side surface covering portion 43 and covers the upper surface 32 of the LED element 3. Yes. The side surface covering portion 43 and the upper surface covering portion 44 are formed with a substantially constant thickness on the surface of the LED element 3. Strictly speaking, the side surface covering portion 43 is slightly narrowed from the upper side to the lower side.

  The lens unit 5 has a dome shape, and is formed in a hemispherical shape in the present embodiment. The lens unit 5 is made of a transparent material having the same or higher refractive index than that of the transparent material 42 of the fluorescent layer 4. The lens unit 5 is preferably made of resin, glass, or the like, and is made of the same material as the transparent material 42 of the fluorescent layer 4. This is because by using the same material as the fluorescent layer 4, the fluorescent layer 4 and the lens unit 5 can be securely adhered.

  According to the light emitting device 1 configured as described above, part of the blue light emitted from the LED element 3 is converted into yellow by the fluorescent layer 4. The light that has entered the lens unit 5 from the fluorescent layer 4 is refracted on the surface of the lens unit 5 and is emitted outside the apparatus. The light emitted from the lens unit 5 to the outside is white light including a blue component and a yellow component.

  Here, since the transparent member 42 and the lens portion 5 of the fluorescent layer 4 are formed of the same material, the transparent member 42 and the lens portion 5 have the same refractive index, and total reflection occurs at the interface between the fluorescent layer 4 and the lens portion 5. In other words, no light is confined in the fluorescent layer 4. Thus, by providing the lens portion 5 having the same refractive index as that of the fluorescent layer 4, the extraction efficiency of the light emitted from the LED element 3 is increased. Even if the refractive index of the lens unit 5 is higher than that of the fluorescent layer 4, the light emitted from the LED element 3 is not totally reflected at the interface between the fluorescent layer 4 and the lens unit 5.

  Further, according to the light emitting device 1 of the present embodiment, since the upper surface covering portion 44 of the fluorescent layer 4 is made thicker than the side surface covering portion 43, the color unevenness of the light extracted from the lens portion 5 can be reduced. Specifically, color unevenness can be reduced by eliminating almost any change in chromaticity near the optical axis (axis perpendicular to the center of the upper surface of the LED element 3).

  Further, according to the light emitting device 1 of the present embodiment, since the transparent member 42 of the fluorescent layer 4 and the lens unit 5 are formed of the same material, the adhesion between the fluorescent layer 4 and the lens unit 5 is high. As a result, air does not remain between the fluorescent layer 4 and the lens unit 5 at the time of manufacturing and no air layer is formed, and optical loss at the interface between the fluorescent layer 4 and the lens unit 5 is minimized. be able to.

  In the embodiment, the combination of the LED element 3 that emits blue light and the fluorescent layer 4 that emits yellow light when excited by the blue light is exemplified. However, the emission color of the LED element 3 and the fluorescent layer 4 is blue. It is not limited to the combination of yellow and yellow. For example, the fluorescent layer 4 may emit yellow and red light, or the LED element 3 may emit green light.

  Moreover, in the said embodiment, although the thing which contains the fluorescent substance particle 41 in the transparent material 42 as the fluorescent layer 4 was shown, it is also possible to use, for example, a glass containing rare earth element ions with the fluorescent layer 4 as the emission center. Is possible. In this case, the lens portion 5 is also preferably made of the same glass as the base material of the fluorescent layer 4.

  In the above embodiment, the LED element 3 is directly mounted on the substrate 2. However, the LED element 3 may be mounted indirectly by interposing a submount, for example. Furthermore, the semiconductor material of the LED element 3 is arbitrary, and other semiconductor materials such as an AlGaAs-based material, a GaAsP-based material, and the like may be used. Furthermore, the LED element 3 may be a face-up type instead of a flip-chip type. Moreover, you may use elements other than the LED element 3 as a light emitting element.

  Moreover, in the said embodiment, although the lens part 5 showed what is a hemispherical dome shape, the lens part 5 may be a dome shape of another shape like a cross-sectional ellipse shape, for example. Further, the relative sizes of the lens unit 5 and the LED element 3 can be arbitrarily changed.

Examples and Comparative Example 1 will be described below.
[Example]
In obtaining the light distribution characteristic data, the light emitting device 1 was manufactured using the 1.0 mm square LED device 3. As the substrate 2, alumina with CuW embedded therein was used, and the circuit pattern of the substrate 2 was formed of AuSn. In addition, the LED element 3 is formed by forming a GaN-based semiconductor layer having a layer configuration of an n-type layer, a light-emitting layer, and a p-type layer in this order on a sapphire substrate having a thickness of 0.375 mm, and a part of the p-type layer and the light-emitting layer. Was removed to expose a part of the n-type layer. V / Al was used as the n electrode of the exposed n type layer, and Rh was used as the p electrode of the p type layer. The fluorescent layer 4 was prepared by dispersing phosphor particles 41 made of YAG in a transparent resin 42 made of silicone resin. The thickness of the fluorescent layer 4 was 250 μm for the side surface covering portion 43 and 475 μm for the upper surface covering portion 44. The lens unit 5 is a hemisphere having a radius of 1.25 mm on the substrate 2 as a silicone resin.

[Comparative Example 1]
FIG. 2 is a cross-sectional explanatory view of a light emitting device showing Comparative Example 1.
As shown in FIG. 2, as Comparative Example 1, a light emitting device 101 having the same thickness of the upper surface covering portion 144 and the side surface covering portion 143 of the fluorescent layer 104 was produced. Specifically, the thickness of the upper surface covering portion 144 of the fluorescent layer 104 was set to 250 μm, and other configurations were the same as those of the light emitting device 1 of the example.

FIG. 3 is a graph showing the relationship between the angle with respect to the optical axis (axis perpendicular to the center of the upper surface of the LED element) and chromaticity of the light emitted outside the apparatus of Example and Comparative Example 1.
As shown in FIG. 3, in Comparative Example 1, the maximum chromaticity was shown when the angle with respect to the optical axis was ± 90 °, and the minimum chromaticity was shown at 0 °. On the other hand, in the examples, the chromaticity is almost the same when the angle with respect to the optical axis is in the range of −60 ° to +60, and almost no difference in chromaticity is recognized in this range. Specifically, when the difference between the maximum chromaticity and the minimum chromaticity is about 0.6 in the comparative example, the difference between the maximum chromaticity and the minimum chromaticity may be about 0.3 in the embodiment. The chromaticity difference could be halved. Speaking only in the range of −60 ° to +60, the chromaticity difference of the example is less than 0.1 while the chromaticity difference of the comparative example is about 0.3.

[Comparative Example 2]
FIG. 4 is a cross-sectional explanatory view of a light emitting device showing a comparative example 2.
As shown in FIG. 4, as Comparative Example 2, a light-emitting device 201 in which the lens unit 5 was omitted from Comparative Example 1 was produced.

FIG. 5 is a graph showing the relationship between the angle with respect to the optical axis and the relative chromaticity of the light emitted to the outside of the devices of Comparative Example 1 and Comparative Example 2.
As shown in FIG. 5, in Comparative Example 1, the maximum chromaticity was shown when the angle with respect to the optical axis was ± 90 °, and the minimum chromaticity was shown at 0 °. In Comparative Example 2, in which the lens unit 5 is omitted from Comparative Example 1, the maximum chromaticity is shown when the angle with respect to the optical axis is ± 90 °, and the minimum chromaticity is shown when ± 50 °. From the data of Comparative Examples 1 and 2, it can be seen that the chromaticity difference increases when the lens unit 5 is provided.

DESCRIPTION OF SYMBOLS 1 Light emitting device 2 Board | substrate 3 LED element 4 Fluorescent layer 5 Lens part 31 Side surface 32 Upper surface 41 Phosphor particle 42 Transparent material 43 Side surface covering part 44 Upper surface coating part 101 Light emitting device 104 Fluorescent layer 143 Side surface coating part 144 Upper surface coating part 201 Light emitting device

Claims (3)

A light emitting device mounted directly or indirectly on a substrate;
A fluorescent layer having a side surface covering portion that covers the side surface of the light emitting element, and an upper surface covering portion that is formed thicker than the side surface covering portion and covers the upper surface of the light emitting element;
A dome-shaped lens portion covering the light emitting element covered with the fluorescent layer on the substrate. The phosphor layer includes phosphor particles and a transparent material in which the phosphor particles are dispersed,
The light emitting device according to claim 1, wherein a refractive index of the lens unit is the same as or larger than a refractive index of the transparent material of the fluorescent layer.   The light emitting device according to claim 2, wherein the lens unit is formed of the same material as the transparent material of the fluorescent layer.

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