JP4534513B2 - Light emitting device - Google Patents

Description

  The present invention relates to a wavelength conversion type light emitting device that generates white light such as white, day white, daylight color, light bulb color, etc. using an LED element as a light source, and in particular, an emission wavelength shift of light emitted from the LED element occurs. The present invention also relates to a light emitting device that does not cause a color shift of white light.

  As a conventional light emitting device, an LED element is used as a light source, and wavelength conversion is performed on white light (hereinafter, referred to as “white light”) emitted from the LED element, such as white, day white, daylight, and bulb color. Accordingly, a wavelength conversion type light emitting device that obtains light of a color different from the original emission color of the LED element, for example, white light, has been put into practical use. In such a light emitting device that emits white light, a GaN-based LED element that emits blue light having a center wavelength of about 450 nm is generally used.

As such a wavelength conversion type light emitting device, a trivalent cerium-activated yttrium aluminate (YAG) phosphor is used as a yellow phosphor that is excited by blue light, and is excited based on irradiation with blue light. There is one in which white light is obtained by mixing the generated yellow light and blue light (for example, see Patent Document 1).
JP 2000-183408 A (FIG. 1)

  However, according to the conventional light emitting device, the excitation light emitted from the phosphor depends on the wavelength characteristics of the light emitted from the LED element. In addition, since the current supplied to the LED element and the electrical characteristics of the LED element may fluctuate due to environmental conditions, aging, etc., when the emission wavelength of the LED element shifts from the center wavelength due to such fluctuation factors, the phosphor is excited. There is a problem in that the efficiency changes, the mixing balance of blue light and yellow light is lost, and color shift of white light occurs.

  Accordingly, an object of the present invention is to provide a light emitting device that does not cause a color shift of white light even if a shift in the emission wavelength of light emitted from an LED element occurs.

In order to achieve the above object, the present invention seals a light emitting element that emits blue light and a light emitting element that is accommodated in the light emitting element, and has a first chromaticity characteristic. A sealing body including a phosphor and a second phosphor, wherein the light emitting element is a GaN-based LED element, and the first phosphor has a chemical formula (Y, Gd, Ce) ₃ (Al , Ga) ₅ O ₁₂ is a garnet-based phosphor mainly composed of a compound, and the second phosphor has a chemical formula (Sr _1- abx Ba _a Ca _b Eu _x ) ₂ SiO. ₄ , a silicate phosphor mainly composed of a compound represented by (0 ≦ a ≦ 0.3, 0 ≦ b ≦ 0.8, 0 <x <1), the first phosphor and the The second phosphor emits yellow light when excited by the blue light, and the light emitting element emits the first injected current. When driven by the second injection current, the light emitting element is varied so as to emit light of the light and a second dominant wavelength of the first dominant wavelength, the first phosphor, the first light emitting The second phosphor is excited by light having a wavelength to emit first light and emits second light having a chromaticity smaller than that of the first light by light having the second emission wavelength. The third light is emitted by being excited by the light having the first emission wavelength, and the fourth light having a higher chromaticity than the third light is emitted by the light having the second emission wavelength, and the light emission Even if there is a deviation in the emission wavelength of the light emitted from the element, the deviation in chromaticity of the light emitted from the first phosphor and the second phosphor is canceled out, and due to the mixture of blue light and yellow light Provided is a light-emitting device in which color shift of white light is suppressed.

  The first phosphor includes at least one element selected from the group consisting of Y, Lu, Sc, La, Gd and Sm and at least one element selected from the group consisting of Al, Ga and In. A garnet-based phosphor activated with cerium can be used.

As the first phosphor, a garnet phosphor mainly composed of a compound represented by the chemical formula (Y, Gd, Ce) ₃ (Al, Ga) ₅ O ₁₂ can be used.

  The second phosphor may be an alkaline earth metal silicate phosphor activated with Eu.

The second phosphor has the formula _{(Sr 1-a-b-} x Ba a Ca b Eu x) 2 SiO 4, (0 ≦ a ≦ 0.3,0 ≦ b ≦ 0.8,0 <x < A silicate phosphor mainly composed of the compound represented by 1) can be used.

  The light emitting element may be configured using an LED element that emits blue light.

  The main body portion may be formed at one end of a pair of lead frames, and the end may have a recess formed in a cup shape and be filled with the sealing body.

  The said main-body part is an insulation part which has the hollow formed in the cup shape, It can be set as the structure with which the hollow formed in the said cup shape is satisfy | filled with the sealing body.

  Each of the electrodes of the light emitting element is electrically connected to a pair of lead frames. The light emitting element, the pair of lead frames, and the sealing body are other light emitting portions formed in a lens shape. It can be set as the structure covered with the sealing body.

  The electrode of the light emitting element may be connected to a lead provided at the bottom of a recess formed in a cup shape of an insulating part by a bump.

  According to the present invention, the first and second phosphors having different excitation characteristics with respect to the change in the excitation spectrum of the light emitted from the LED element are included in the sealing body. Even if the excitation characteristic of one of the phosphors is shifted from the center wavelength, the emission of yellow light is compensated by the excitation characteristic of the other phosphor, so that the deviation of chromaticity is offset and the color deviation of white light is offset. It is suppressed.

[First Embodiment]
FIG. 1 is a cross-sectional view showing a light emitting device package according to a first embodiment of the present invention. The light emitting device package 1 includes a resin housing 103, a GaN-based semiconductor light-emitting device 106 mounted thereon, and an epoxy resin sealing body 111 provided so as to cover the GaN-based semiconductor light-emitting device 106.

  The resin housing 103 is integrally formed with leads 101 and 102 formed from a lead frame. The leads 101 and 102 are arranged so that one ends of the leads 101 and 102 face each other. The other ends of the leads 101 and 102 extend in opposite directions and are led out from the resin housing 103 to the outside.

  The resin housing 103 is provided with a mortar-shaped reflecting surface 104, and the GaN-based semiconductor light emitting element 106 is mounted on the bottom surface. The planar shape of the mortar-shaped reflecting surface 104 can be, for example, substantially elliptical or circular.

The GaN-based semiconductor light-emitting device 106 includes a GaN-based semiconductor layer (for example, an n ⁺ -GaN layer, an n-GaN layer, an MQW layer (multiple GaN barrier layers and InGaN well layers) epitaxially grown on a sapphire (Al ₂ O ₃ ) substrate. A quantum well structure with a peak emission wavelength of 460 nm), a p-AlGaN layer, a p ⁺ -GaN layer), an n − electrode formed on the n ⁺ -GaN layer, and a p ⁺ -GaN layer. The Al ₂ O ₃ substrate side is mounted on the lead 101 on the bottom surface of the mortar-shaped reflecting surface 104 by an adhesive 107 such as silver (Ag) paste. The GaN-based semiconductor light emitting device 106 has an n-electrode and a p-electrode (not shown), and is connected to leads 101 and 102 by bonding wires 108 and 109 such as gold (Au) wires, respectively.

The epoxy resin encapsulant 111 filled in the mortar-shaped reflective surface 104 contains a YAG phosphor 110A and a silicate phosphor 110B. The YAG-based phosphor 110A includes at least one element selected from the group consisting of Y, Lu, Sc, La, Gd, and Sm and at least one element selected from the group consisting of Al, Ga, and In. A garnet-based phosphor activated with cerium, for example, Y ₃ Al ₅ O ₁₂ : Ce. Further, silicate phosphor 110B has the formula _{(Sr 1-a-b-} x Ba a Ca b Eu x) 2 SiO 4, (0 ≦ a ≦ 0.3,0 ≦ b ≦ 0.8,0 <x <1) is a phosphor mainly composed of a compound represented by <1), for example, Sr _1.9 Ba _0.02 Ca _0.08 SiO ₄ : Eu. This phosphor has the property of being easily dispersed uniformly in the resin.

  In the present invention, the emission peak wavelength of the GaN-based semiconductor light-emitting element 106 is, for example, 460 nm, and the YAG-based phosphor 110A and the silicate phosphor 110B can be excited by primary light of 460 nm. In addition to the YAG phosphor 110A and the silicate phosphor 110B, for example, the phosphor is a combination of a phosphor emitting red light, a phosphor emitting green light, or a phosphor emitting blue light. May be.

  In the above configuration, the primary light emitted from the GaN-based semiconductor light-emitting element 106 is extracted after being wavelength-converted by the YAG-based phosphor 110A and the silicate phosphor 110B without being directly extracted outside. That is, the blue light emitted from the GaN-based semiconductor light-emitting element 106 excites the YAG-based phosphor 110A and the silicate phosphor 110B, thereby radiating yellow from the YAG-based phosphor 110A and the silicate phosphor 110B. When mixed with light, white light is produced. This white light is emitted from the epoxy resin sealing body 111 to the outside.

  The GaN-based semiconductor light emitting device 106 in the first embodiment shows a tendency that the dominant wavelength changes from about 475 nm to about 469 nm when the forward current changes from 1 mA to 30 mA. Further, as the dominant wavelength changes, the chromaticity tends to increase by 0.005 in the X direction in the two-dimensional coordinate space, and tends to decrease by −0.07 in the Y-axis direction.

  FIG. 2 is a diagram illustrating a change in relative chromaticity when the current value to the GaN-based semiconductor light-emitting element of the light-emitting element package is changed. Here, the light emitting element package 1 is formed using an epoxy resin sealing body 111 having a composition of 2 wt% of YAG phosphor 110A and 23 wt% of silicate phosphor 110B with respect to 75 wt% of epoxy resin. When the current supplied to the GaN-based semiconductor light-emitting element 106 is changed from 1 mA to 30 mA, the chromaticity of the YAG-based phosphor 110A is as small as −0.005 in the X-axis direction and −0.05 in the Y-axis direction. In the silicate phosphor 110B, the chromaticity tends to increase by 0.02 in the X-axis direction and 0.01 in the Y-axis direction, but the two phosphors are mixed. The change in chromaticity due to this is 0.005 in the X-axis direction and almost no change in the Y-axis direction. In the present embodiment in which these two phosphors are mixed, the chromaticity is changed. The change of is suppressed to a level that can be almost ignored.

  According to the light emitting device package of the first embodiment described above, by mixing a plurality of phosphors having different chromaticity change characteristics into the epoxy resin sealing body 111, there is a deviation in the emission wavelength of the GaN-based semiconductor light emitting device 106. Even if it exists, since the deviation of the chromaticity of the excitation light emitted from the YAG-based phosphor 110A and the silicate phosphor 110B is offset, the mixing of blue light and yellow light can be stabilized, and the white light Occurrence of color misregistration can be suppressed.

  Note that the epoxy resin sealing body 111 described above can be formed of other resin materials such as a silicon resin material as long as it does not impair light transmittance and workability.

[Second Embodiment]
FIG. 3 is a cross-sectional view showing a light emitting device package according to a second embodiment of the present invention. Note that portions having the same configuration as those of the first embodiment are denoted by the same reference numerals. This light emitting device package encapsulates a ceramic (Al ₂ O ₃ ) housing 40, a GaN-based semiconductor light-emitting device 20 housed in the Al ₂ O ₃ housing 40 and flip-chip bonded, and the GaN-based semiconductor light-emitting device 20. An epoxy resin sealing body 111 is used.

The Al ₂ O ₃ housing 40 has a metallized mortar-like reflecting surface 41, and tungsten wirings 15 and 16 are formed on the bottom surface by printed wiring. The tungsten wirings 15 and 16 are electrically connected to the leads 11 and 12 on the bottom surface of the Al ₂ O ₃ housing 40 via the tungsten wirings 13 and 14 formed on the wall surface of the via hole.

The GaN-based semiconductor light-emitting element 20 has the same configuration as that of the GaN-based semiconductor light-emitting element 106 described in the first embodiment, and includes a GaN-based semiconductor layer 22 epitaxially grown on the Al ₂ O ₃ substrate 21, and n ⁺ The n-electrode 23 is formed on the GaN layer and the p-electrode 24 is formed on the p ⁺ -GaN layer. The n-electrode 23 is connected via the solder bumps 25 and 26. It is connected to the tungsten wiring 16 and mounted on the bottom surface of the mortar-shaped reflecting surface 41 of the Al ₂ O ₃ housing 40.

  The epoxy resin sealing body 111 contains a YAG phosphor 110A and a silicate phosphor 110B, as in the first embodiment.

In the above configuration, the leads 11 and 12 are connected to a power supply unit (not shown) and energized, whereby the GaN-based semiconductor light emitting element 20 is energized via the solder bumps 25 and 26. The GaN-based semiconductor light-emitting element 20 emits light in an MQW layer (not shown) and emits blue light having an emission wavelength of 460 nm from the Al ₂ O ₃ substrate side. The YAG phosphor 110A and the silicate phosphor 110B contained in the epoxy resin encapsulant 111 are excited by blue light and emit yellow light. When the blue light and the yellow light are mixed in the epoxy resin sealing body 111, white light is generated and emitted to the outside of the Al ₂ O ₃ housing 40.

  According to the second embodiment described above, since the flip-chip type GaN-based semiconductor light emitting device 20 is used in addition to the preferable effects of the first embodiment, the blue light generated in the MQW layer can be converted into the GaN-based semiconductor. It can be efficiently taken out from the layer, and high brightness can be realized.

[Third Embodiment]
FIG. 4 is a sectional view showing an LED lamp according to a third embodiment of the present invention. Note that portions having the same configuration as those of the second embodiment are denoted by the same reference numerals. The LED lamp 50 includes a lead frame 51A, 51B made of copper, a cup 52 provided as a recess having a reflecting surface 52B at the end of the lead frame 51A, and a bottom surface of the cup 52 by a conductive adhesive 54 such as Ag paste. The submount 53 bonded to 52A, the flip chip type GaN-based semiconductor light emitting element 20 electrically connected to the submount 53 via the gold bump 55, the submount 53, and the lead frame 51B are electrically connected. Epoxy resin sealing having light transmissivity for sealing the GaN-based semiconductor light-emitting element 20 by filling the cup 52 with the wire 56 to be connected, the YAG-based phosphor 110A and the silicate phosphor 110B. Body 57, lead frame 51A and lead frame 51B sealed with epoxy resin sealing body 57 And and a transparent epoxy resin sealing body 58 for sealing integrally a wire 56, the surface of the epoxy resin sealing body 58 is a convex lens-like optical shape portion 58A is formed.

  The GaN-based semiconductor light-emitting element 20 and the epoxy resin sealing body 111 are the same as those in the second embodiment shown in FIG. The submount 53 is made of aluminum nitride (AlN) having excellent thermal conductivity. The submount 53 has a tungsten wiring (not shown) formed on the bonding surface with the gold bump 55 and the bonding surface with the conductive adhesive 54. The tungsten wiring on the p-electrode side is the same as the tungsten wiring on the bonding surface side. They are electrically connected by via holes. Further, the tungsten wiring on the n-electrode side is electrically connected to the lead frame 51 </ b> B by a wire 56.

In the above configuration, the GaN-based semiconductor light-emitting element 20 is energized through the submount 53 by connecting the lead frames 51A and 51B to a power supply unit (not shown) and energizing. The GaN-based semiconductor light-emitting element 20 emits light in an MQW layer (not shown) and emits blue light having an emission wavelength of 460 nm from the Al ₂ O ₃ substrate side. The YAG phosphor 110A and the silicate phosphor 110B contained in the epoxy resin encapsulant 111 are excited by blue light and emit yellow light. When the blue light and the yellow light are mixed in the epoxy resin sealing body 111, white light is generated and radiated to the outside of the cup 52, and a predetermined radiation is emitted from the optical shape portion 58A via the epoxy resin sealing body 58. Radiated in the direction.

  According to the above-described third embodiment, in addition to the preferable effects of the second embodiment, heat generated by light emission of the GaN-based semiconductor light-emitting element 20 is transmitted via the submount 53 and lead frame 51A made of AlN. It is possible to dissipate heat efficiently, and change in emission wavelength due to heat can be reduced. Even if the emission wavelength changes, since the YAG phosphor 110A and the silicate phosphor 110B having different chromaticity change characteristics are mixed in the resin sealing body, the chromaticity deviation of the excitation light is offset. The occurrence of color shift of white light can be suppressed.

  In the third embodiment, the configuration in which the YAG phosphor 110A and the silicate phosphor 110B are mixed with the epoxy resin sealing body 57 that seals the cup 52 has been described. The body 57 is provided with a cap-like phosphor-containing resin portion that does not contain these phosphors and covers the outer periphery of the epoxy resin sealing body 58, and contains YAG phosphor 110A and silicate phosphor 110B. May be.

  According to this configuration, since the phosphor-containing resin portion containing the YAG phosphor 110A and the silicate phosphor 110B can be formed thin, the external radiation efficiency of white light can be improved.

[Fourth Embodiment]
FIG. 5 is an overall view of a light emitting device according to the fourth embodiment of the present invention. The light emitting device 60 includes an LED lamp 62 using the GaN-based semiconductor light emitting element 20 as a light source, and a light reflector 61 that reflects light emitted from the LED lamp 62 in a right angle direction.

  The LED lamp 62 is formed by molding the GaN-based semiconductor light emitting element 20 with an epoxy resin sealing body 58, and has a dome-shaped optical shape portion 58A so as to collect light in a desired direction. .

  The light reflector 61 includes an epoxy resin member 61A that includes a YAG phosphor 110A and a silicate phosphor 110B and is configured in a flat plate shape, and an aluminum vapor deposition portion 61B formed on the epoxy resin member 61A by a thin film forming method. And have.

  In the light emitting device 60 according to the fourth embodiment, when the blue light emitted from the LED lamp 62 enters the light reflector 61, the YAG phosphor 110A and the silicate phosphor 110B are blue light in the epoxy resin member 61A. Excited to produce yellow light. The yellow light is reflected by the vapor deposition part 61B and reflected in a right angle direction. Further, the blue light that does not reach the phosphor is reflected in the perpendicular direction by the vapor deposition part 61B. White light is generated based on the mixture of yellow light and blue light.

  According to the above-described fourth embodiment, even if the emission wavelength of the GaN-based semiconductor light-emitting element 106 is shifted from the center wavelength, the chromaticity deviation of the excitation light is canceled as described in the first embodiment. Therefore, even if the wavelength conversion unit containing the phosphor is separated from the light source, the mixing property of blue light and yellow light can be stabilized and the occurrence of color shift of white light can be suppressed. be able to.

  In the fourth embodiment, the configuration in which the light reflector 61 is provided as the wavelength conversion unit has been described. However, for example, a configuration in which the light transmission type wavelength conversion unit is provided separately from the light source may be used.

It is sectional drawing which shows the light emitting element package which concerns on the 1st Embodiment of this invention. It is a figure which shows the relative chromaticity change when changing the electric current value to the GaN-type semiconductor light emitting element of a light emitting element package. It is sectional drawing which shows the light emitting element package which concerns on the 2nd Embodiment of this invention. It is sectional drawing which shows the LED lamp which concerns on the 3rd Embodiment of this invention. It is a general view of the light-emitting device which concerns on the 4th Embodiment of this invention.

Explanation of symbols

1, the light emitting device package 11, the lead 13, the tungsten wire 15, tungsten wires 16, tungsten wires 20, GaN-based semiconductor light-emitting element 21, ceramic _(Al 2 _{O 3)} substrate 22, GaN-based semiconductor layer 23, n-electrodes 24, p-electrodes 25 and 26, solder bumps 40, ceramics (Al ₂ O ₃ ) housing 41, mortar-shaped reflecting surface 50, LED lamp 51A, lead frame 51B, lead frame 52, cup 52A, bottom surface 52B, reflecting surface 53 , Submount 54, conductive adhesive 55, gold bump 56, wire 57, epoxy resin sealing body 58, epoxy resin sealing body 58A, optical shape part 60, light emitting device 61A, epoxy resin member 61, light reflector 61B , Evaporation unit 62, LED lamps 101 and 102, lead 103, tree Fat housing 104, bowl-shaped reflecting surface 106, GaN-based semiconductor light-emitting element 107, conductive adhesive 108, bonding wire 110A, YAG-based phosphor 110B, silicate phosphor 111, epoxy resin encapsulant

Claims (5)

A main body that houses a light emitting element that emits blue light;
Sealing the light-emitting element accommodated in the main body, and having a first phosphor and a second phosphor having different chromaticity characteristics,
The light emitting element is a GaN-based LED element,
The first phosphor is a garnet phosphor mainly composed of a compound represented by the chemical formula (Y, Gd, Ce) ₃ (Al, Ga) ₅ O ₁₂ .
The second phosphor has the formula _{(Sr 1-a-b-} x Ba a Ca b Eu x) 2 SiO 4, (0 ≦ a ≦ 0.3,0 ≦ b ≦ 0.8,0 <x < 1) a silicate phosphor mainly composed of the compound represented by
The first phosphor and the second phosphor emit yellow light when excited by the blue light,
When the light emitting element is driven by the first injection current and the second injection current, the light emitting element is varied so as to emit light of the light and a second dominant wavelength of the first dominant wavelength,
The first phosphor is excited by the light having the first emission wavelength to emit the first light, and has a second chromaticity smaller than that of the first light by the light having the second emission wavelength. Radiate light,
The second phosphor is excited by light having a first emission wavelength to emit third light, and has a chromaticity greater than that of the third light by the light having the second emission wavelength. Radiate light,
Even if there is a deviation in the emission wavelength of the light emitted from the light emitting element, the deviation in chromaticity of the light emitted from the first phosphor and the second phosphor is canceled, and the blue light and the yellow light A light emitting device characterized in that color shift of white light due to mixing is suppressed. Said body portion, claim 1, characterized in that is formed on one end of the pair of lead frames, wherein the end is filled with the sealing body has a recess formed in a cup-shaped The light emitting device according to 1. The light emitting device according to claim 1 , wherein the main body is an insulator having a depression formed in a cup shape, and the depression formed in the cup shape is filled with the sealing body. . The electrodes of the light emitting element are electrically connected to a pair of lead frames,
The light emitting device according to claim 1, wherein the light emitting element, the pair of lead frames, and the sealing body is covered by other sealing body light emitting unit is formed in a lens shape. The light emitting device according to claim 1 , wherein the electrode of the light emitting element is connected to a lead provided at a bottom of a recess formed in a cup shape of an insulating portion by a bump.

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