Light-emitting device

Abstract

To provide a light-emitting device capable of efficiently dissipating heat from a phosphor layer.SOLUTION: A light-emitting device 1 includes: multiple light-emitting elements 10 placed at predetermined intervals; a first phosphor layer 20 made of phosphor ceramics; and filling materials 30, 30A that are formed between adjacent light emitting elements 10 covering the sides of the multiple light emitting elements 10. The first phosphor layer 20 is a plate-like member that covers the light emission surfaces of the multiple light-emitting elements 10, and the first phosphor layer 20 is arranged to abut against the light-emitting element 10 and the filling materials 30, 30A.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] The present invention relates to a light emitting device. [Background technology]

[0002] In recent years, light-emitting devices that combine light-emitting elements such as light-emitting diodes (LEDs) or laser diodes (LDs) with phosphors have become widespread. Such light-emitting devices are used as light sources for image display devices such as displays and projectors, and lighting devices.

[0003] Patent Document 1 discloses a light emitting device including a light emitting diode and a phosphor layer containing a phosphor. Specifically, the light emitting device includes a light emitting diode electrically joined onto a circuit board, a housing surrounding the light emitting diode, and a light emitting device component having an encapsulating resin layer capable of encapsulating the light emitting diode and a phosphor layer formed on the surface of the encapsulating resin layer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2012-28666 A Summary of the Invention [Problem to be solved by the invention]

[0005] Here, in a light-emitting device combining a light-emitting element and a phosphor, the temperature of the phosphor layer increases due to heat emitted from the phosphor, and as a result, a phenomenon (temperature quenching) in which the emission intensity decreases over time may occur. Therefore, in order to suppress temperature quenching, it is necessary to dissipate heat from the phosphor layer. However, in Patent Document 1, since a sealing resin layer with low thermal conductivity exists between the phosphor layer and the light-emitting diode, there is a problem that the heat dissipation of the phosphor layer is insufficient and it is difficult to suppress the temperature quenching of the phosphor.

[0006] The present invention has been made in view of the problems inherent in the conventional techniques, and an object of the present invention is to provide a light emitting device capable of efficiently dissipating heat from a phosphor layer. [Means for solving the problem]

[0007] In order to solve the above problems, a light emitting device according to an embodiment of the present invention includes a plurality of light emitting elements arranged at a predetermined interval, a first phosphor layer made of phosphor ceramics, and a filler member covering the side surfaces of the plurality of light emitting elements and provided between adjacent light emitting elements. The first phosphor layer is a plate-like member covering the light emission surfaces of the plurality of light emitting elements, and the first phosphor layer is arranged so as to abut against the plurality of light emitting elements and the filler member. Effect of the Invention

[0008] According to the present disclosure, it is possible to provide a light emitting device capable of efficiently dissipating heat from the phosphor layer. [Brief description of the drawings]

[0009] [Figure 1A] 1 is a cross-sectional view illustrating an example of a light emitting device according to a first embodiment. [Figure 1B] 1B is a plan view showing the light emitting device shown in FIG. 1A in plan view. FIG. [Figure 1C] 1C is a plan view showing the light emitting device of FIG. 1B in a state where a first phosphor layer is removed. [Figure 2A] 4 is a cross-sectional view for explaining a heat dissipation path in the light emitting device according to the first embodiment. FIG. [Figure 2B] FIG. 4 is a plan view for explaining a heat dissipation path in the light emitting device according to the first embodiment. [Figure 3A] FIG. 4 is a cross-sectional view showing an example of a light-emitting device according to a second embodiment. [Figure 3B] 3C is a plan view showing the light emitting device in FIG. 3B in plan view. FIG. [Figure 4] FIG. 11 is a cross-sectional view showing another example of the light emitting device according to the second embodiment. [Diagram 5] FIG. 11 is a cross-sectional view showing an example of a light-emitting device according to a third embodiment. [Figure 6] FIG. 13 is a diagram showing the results of a beam profile in the light emitting device of Example 1-1. [Figure 7] FIG. 13 is a diagram showing the results of the beam profile in the light emitting device of Example 1-2. [Figure 8] FIG. 11 is a front view showing the overall shape of an analysis model used in a CAE analysis in Example 2. [Figure 9] FIG. 2 is a perspective view showing a light-emitting module in an analysis model used in a CAE analysis. [Figure 10A] FIG. 2 is a plan view showing a light-emitting module in an analysis model used in a CAE analysis. [Figure 10B] FIG. 2 is a front view showing a light-emitting module in an analysis model used in a CAE analysis. [Figure 11] FIG. 2 is a schematic diagram showing a light emitting device in an analysis model used in a CAE analysis. [Figure 12] FIG. 2 is a plan view for explaining the arrangement of light-emitting elements and dam materials in a light-emitting device in an analysis model used in a CAE analysis. [Figure 13] FIG. 2 is a plan view for explaining the arrangement of a phosphor layer, a filler material, and a dam material in a light-emitting device in an analysis model used in a CAE analysis. [Figure 14] 1 is a table showing the structures and CAE analysis results of light emitting devices according to Examples 2-1 to 2-3 and Comparative Examples 2-1 to 2-3. [Figure 15] FIG. 2 is a contour diagram showing the temperature distribution on the surface on the light emission surface side of the first phosphor layer in CAE analysis of the light emitting devices of Example 2-1, Comparative Example 2-1, and Comparative Example 2-3. [Figure 16] 16 is a graph showing the relationship between the diagonal distance of the first phosphor layer and the surface temperature of the first phosphor layer along the dotted line in FIG. [Figure 17] FIG. 2 is a contour diagram showing the temperature distribution on the surface of the light emission surface side of the first phosphor layer and the temperature distribution on the surface of the light emission surface side of the second phosphor layer in a CAE analysis of the light emitting devices of Example 2-2, Example 2-3, and Comparative Example 2-2. [Figure 18] 18 is a graph showing the relationship between the diagonal distance of the first phosphor layer and the surface temperature of the first phosphor layer along the dotted line in FIG. 17. [Figure 19] 18 is a graph showing the relationship between the diagonal distance of the second phosphor layer and the surface temperature of the second phosphor layer along the dotted line in FIG. 17. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the light emitting device according to the present embodiment will be described in detail with reference to the drawings. Note that the dimensional ratios in the drawings are exaggerated for the convenience of explanation and may differ from the actual ratios.

[0011] [First embodiment] As shown in Figures 1A and 1B, the light-emitting device 1 of this embodiment includes a plurality of light-emitting elements 10, a first phosphor layer 20 made of phosphor ceramics, and a filling member 30 that covers the side surfaces of the plurality of light-emitting elements 10.

[0012] The plurality of light-emitting elements 10 are mounted on a main surface 41 of a flat substrate 40. The substrate 40 is provided with metal wiring for supplying power to the light-emitting elements 10 and electrodes for supplying power from an external device to the light-emitting elements 10. The material constituting the substrate 40 is not particularly limited, but the substrate 40 may be a ceramic substrate, a resin substrate, a glass substrate, or a metal-based substrate in which a metal plate is coated with an electrical insulating film.

[0013] The substrate 40 may be a white substrate having a high light reflectance. By using a white substrate, the light emitted by the light emitting element 10 can be reflected on the surface of the substrate 40, thereby improving the light extraction efficiency. A white ceramic substrate made of alumina can be used as the substrate 40. The shape of the substrate 40 in plan view is not particularly limited, but may be rectangular as shown in FIG. 1B, or may be circular or polygonal.

[0014] The light emitting elements 10 may be light emitting diodes (LEDs) or laser diodes (LDs). In this embodiment, as shown in FIG. 1C, four light emitting elements 10 are mounted on a substrate 40 and arranged in two rows in the X-axis direction and two rows in the Y-axis direction. Adjacent light emitting elements 10 are spaced apart from each other with a predetermined gap therebetween. As described later, a filling member 30 is filled between adjacent light emitting elements 10.

[0015] The light-emitting element 10 has an upper surface 11 which is a light-emitting surface from which excitation light is emitted. The light-emitting elements 10 are electrically connected so as to be turned on and off collectively. Specifically, adjacent light-emitting elements 10 are connected chip-to-chip by a bonding wire for power supply. Note that, although the number of light-emitting elements 10 is four in FIG. 1C, it is not particularly limited as long as it is more than one.

[0016] The wavelength of the excitation light emitted by the light emitting element 10 is not particularly limited, but the peak wavelength of the excitation light can be 430 nm or more and 460 nm or less, and can also be 445 nm or more and 460 nm or less. When the peak wavelength of the excitation light is 430 nm or more, the color rendering of the light emitted by the light emitting device 1 can be improved. Furthermore, when the peak wavelength of the excitation light is 460 nm or less, the light emitting efficiency of the light emitting device 1 can be improved. Note that the excitation light emitted by the light emitting element 10 is not limited to blue light, and may be ultraviolet light, green light, or red light. Furthermore, the multiple light emitting elements 10 may be a combination of a light emitting element that emits ultraviolet or green light and a light emitting element that emits blue light, or a combination of a light emitting element that emits blue light and a light emitting element that emits red light.

[0017] The first phosphor layer 20 is made of phosphor ceramics obtained by sintering a phosphor. Since phosphor ceramics are made only of inorganic materials with excellent thermal conductivity, they can dissipate heat emitted from the phosphors in the phosphor ceramics, suppress temperature quenching of the phosphors, and increase the light output.

[0018] For example, (Ga,Sc)2O3:Cr3+ The thermal conductivity of phosphor ceramics made by sintering phosphors is about 8.6 W / m K, and Gd3Ga2(GaO4)3:Cr 3+ The thermal conductivity of phosphor ceramics made by sintering phosphors is about 6.5 W / m K. 12 :Ce 3+ The thermal conductivity of phosphor ceramics, which are made by sintering phosphors, is about 10 W / m·K. In contrast, the thermal conductivity of a wavelength conversion material in which phosphor particles are dispersed in a translucent material such as silicone resin is about 0.2 W / m·K. As such, the thermal conductivity of phosphor ceramics is better than that of the above-mentioned wavelength conversion materials, so the heat generated by the phosphor can be dissipated efficiently.

[0019] The phosphor contained in the first phosphor layer 20 can be an inorganic phosphor that absorbs the excitation light emitted from the light emitting element 10 and emits fluorescence having a longer wavelength than the excitation light. As such a phosphor, at least one of a blue phosphor, a green phosphor, a yellow phosphor, and a red phosphor can be used.

[0020] The blue phosphor has an emission peak in the wavelength region of 470 nm to 500 nm, the green phosphor has an emission peak in the wavelength region of 500 nm to 540 nm, and the yellow phosphor has an emission peak in the wavelength region of 545 nm to 595 nm. 10 O 17 :EU 2+ , CaMgSi2O6:Eu 2+ , Ba3MgSi2O8:Eu 2+ , Sr 10 (PO4)6Cl2:Eu 2+ Examples of green phosphors include (Ba,Sr)2SiO4:Eu 2+ , Ca8Mg(SiO4)4Cl2:Eu 2+ , Ca8Mg(SiO4)4Cl2:Eu 2+ ,Mn 2+ Examples of yellow phosphors include (Sr,Ba)2SiO4:Eu 2+ , (Y,Gd)3Al5O 12 :Ce3+ , Ca-α-SiAlON:Eu 2+ Examples include:

[0021] The red phosphor is excited by the light emitted from the light emitting element 10 or at least one of the green phosphor and the yellow phosphor, and emits red light. The red phosphor has an emission peak in the wavelength range of 600 nm to 650 nm. The red phosphor is, for example, Sr2Si5N8:Eu 2+ , CaAlSiN3:Eu 2+ (CASN), SrAlSi4N7:Eu 2+ , CaS:Eu 2+ , La2O2S:Eu 3+ , Y3Mg2(AlO4)(SiO4)2:Ce 3+ Examples include:

[0022] The phosphor contained in the first phosphor layer 20 may be a near-infrared phosphor. For example, an inorganic phosphor having a fluorescence peak in a wavelength range of 750 nm or more and less than 1500 nm, particularly 780 nm or more and less than 900 nm, can be used as the near-infrared phosphor. Representative examples of such near-infrared phosphors include phosphors activated with transition metal ions and phosphors activated with rare earth ions. Specifically, the near-infrared phosphor is Cr 3+ The rare earth activated phosphor may be at least one of a Tm activated phosphor and a rare earth activated phosphor. 3+ , Er 3+ , Nd 3+ and Yb 3+ The phosphor may be activated with at least one selected from the group consisting of:

[0023] In near infrared phosphors, the preferred fluorescent ion is Cr 3+ The fluorescent ion is Cr. 3+ By using the above, it is easy to obtain a near-infrared phosphor that absorbs blue light and converts it into a near-infrared light component. In addition, it is easy to change the light absorption peak wavelength and / or the fluorescence peak wavelength depending on the type of the host, which is advantageous in changing the excitation spectrum shape and the fluorescence spectrum shape.

[0024] The near infrared phosphor is Cr 3+ Specifically, the near-infrared phosphor is a phosphor comprising a base material selected from the group consisting of borates, phosphates, silicates, aluminates, gallates, germanates, tungstates, and metal oxides, and a Cr 3+ It is preferable that the phosphor is activated with CeSc3(BO3)4:Cr. 3+ , (La,Y,Sc)4(BO3)4:Cr 3+ , LaSc3(BO3)4:Cr 3+ , ScBO3:Cr 3+ , KInP2O7:Cr 3+ , Sr3InP3O 12 :Cr 3+ , Sr9In(PO4)7:Cr 3+ , NaScSi2O6:Cr 3+ , Mg2Al4Si5O 18 :Cr 3+ , La3(Ga,Gd)5GeO 14 :Cr 3+ , La3(Ga,Al)5SiO 14 :Cr 3+ , LaMgGa 11 O 19 :Cr 3+ , Mg3Ga2GeO8:Cr 3+ , Li(In,Sc)Ge2O6:Cr 3+ , Zn3(Ga,Al)Ge2O 10 :Cr 3+ , LiMg2InGe2O8:Cr 3+ , NaCa2GaGe5O 14 :Cr 3+ , NaGdMgWO6:Cr 3+ , (Ga,Sc)2O3:Cr 3+ , LaLuO3:Cr 3+ , Ba3Sc4O9:Cr 3+ , Zn2SnO4:Cr 3+ , LiIn2SbO6:Cr 3+ , LiSrAlF6:Cr 3+ It can be at least one selected from the group consisting of:

[0025] It is also preferable that the near-infrared phosphor is a phosphor having a garnet-type crystal structure, which has a proven track record in practical use. 3+ The phosphor having a garnet-type crystal structure activated by RE3B'2(AlO4)3:Cr 3+ , RE3B'2(GaO4)3:Cr 3+ Here, RE is a rare earth element, and B' is at least one element selected from Al, Ga, and Sc.

[0026] The near-infrared phosphor is preferably at least one of a rare earth aluminum garnet phosphor and a rare earth gallium garnet phosphor. Specifically, the near-infrared phosphor is Y3Al2(AlO4)3:Cr 3+ , La3Al2(AlO4)3:Cr 3+ , Gd3Al2(AlO4)3:Cr 3+ , Y3Ga2(AlO4)3:Cr 3+ , La3Ga2(AlO4)3:Cr 3+ , Gd3Ga2(AlO4)3:Cr 3+ , Y3Sc2(AlO4)3:Cr 3+ , La3Sc2(AlO4)3:Cr 3+ , Gd3Sc2(AlO4)3:Cr 3+ , Y3Ga2(GaO4)3:Cr 3+ , La3Ga2(GaO4)3:Cr 3+ , Gd3Ga2(GaO4)3:Cr 3+ , Y3Sc2(GaO4)3:Cr 3+ , La3Sc2(GaO4)3:Cr 3+ ,Gd3Sc2(GaO4)3:Cr 3+ It is preferable that the at least one selected from the group consisting of:

[0027] 1A and 1C, the filling member 30 is formed on the main surface 41 of the substrate 40 so as to cover the periphery of the plurality of light-emitting elements 10. Specifically, the filling member 30 is disposed so as to be in contact with the periphery of each light-emitting element 10 and to cover the entire periphery of the light-emitting element 10 when viewed in a plan view. The filling member 30 is also provided so as to fill the gaps between adjacent light-emitting elements 10.

[0028] The material of the filling member 30 is not particularly limited as long as it is made of a material having thermal conductivity. In addition, the filling member 30 preferably contains a reflective material that reflects light. When the filling member 30 contains a reflective material, the filling member 30 reflects the excitation light emitted from the light emitting element 10 and the fluorescence emitted from the phosphor, and therefore the light emitting efficiency of the light emitting device 1 can be improved.

[0029] For example, a curable white silicone resin can be used as the filling member 30. The curable white silicone resin is a resin obtained by dispersing a white pigment in a silicone resin. As the white pigment, at least one selected from the group consisting of titanium dioxide, alumina, rare earth oxides such as yttrium oxide, zinc sulfate, zinc oxide, and magnesium oxide can be used. In addition, the curable white silicone resin may contain an inorganic filler in order to increase the strength and thermal conductivity of the cured product. As the inorganic filler, at least one selected from the group consisting of fused silica, crystalline silica, alumina, silicon nitride, aluminum nitride, boron nitride, glass fiber, and antimony trioxide can be used.

[0030] As shown in FIGS. 1A to 1C, a dam material 50 serving as a side wall is provided on the outer periphery of the filling member 30 provided around the plurality of light emitting elements 10. The dam material 50 stands in the Z-axis direction from the main surface 41 of the substrate 40 and is formed in a rectangular shape in a plan view so as to cover the entire outer periphery of the filling member 30. By providing the dam material 50 on the entire outer periphery of the filling member 30, the filling member 30 can be stably held inside the dam material 50. Note that, as shown in FIG. 1A, the height of the dam material 50 in the Z-axis direction can be made higher than the filling member 30 and the stack of the light emitting elements 10 and the first phosphor layer 20.

[0031] The material constituting the dam material 50 is not particularly limited, and may be at least one selected from the group consisting of metals, resins, and ceramics. In addition, since the dam material 50 preferably has light reflectivity, it is more preferable that the dam material 50 is made of a material having light reflectivity.

[0032] In the light emitting device 1, the first phosphor layer 20 is laminated on the upper surface 11 of the plurality of light emitting elements 10, and is a plate-like member covering the light emission surfaces of the plurality of light emitting elements 10. That is, as shown in FIG. 1B, the first phosphor layer 20 covers not only the light emission surfaces of the four light emitting elements 10, but also the upper surface of the filling member 30A located between the adjacent light emitting elements 10. The first phosphor layer 20 may be laminated directly on the upper surface 11 of the plurality of light emitting elements 10, or may be laminated via an adhesive layer. The adhesive layer for bonding the first phosphor layer 20 and the light emitting elements 10 is not particularly limited, and at least one of an inorganic adhesive and an organic adhesive having optical transparency can be used, for example.

[0033] The first phosphor layer 20 is in contact with the upper surfaces 11 of the light-emitting elements 10 and the upper surface 31A of the filler 30A located between the adjacent light-emitting elements 10. That is, the lower surface 21 of the first phosphor layer 20 may be in direct contact with the upper surfaces 11 of the light-emitting elements 10 and the upper surface 31A of the filler 30A. In addition, when the first phosphor layer 20 is bonded to the light-emitting elements 10 by an adhesive layer, the first phosphor layer 20 may be in contact with the upper surfaces 11 of the light-emitting elements 10 and the upper surface 31A of the filler 30A located between the adjacent light-emitting elements 10 via an adhesive layer. In this way, by the first phosphor layer 20 being in contact with the upper surfaces 11 of the light-emitting elements 10 and the upper surface 31A of the filler 30A, heat generated in the first phosphor layer 20 can be conducted to the light-emitting elements 10 and the filler 30A to be dissipated, as described later.

[0034] In the light emitting device 1, when the light emitting surface side of the plurality of light emitting elements 10 is viewed in plan, it is preferable that the outer dimensions of the first phosphor layer 20 are substantially equal to the outer dimensions of the plurality of light emitting elements 10. Specifically, as shown in FIG. 1B and FIG. 1C, it is preferable that the outer dimension W1 of the first phosphor layer 20 in the Y-axis direction is substantially equal to the outer dimension W3 of the two light emitting elements 10 including the filling member 30A. Similarly, it is preferable that the outer dimension W2 of the first phosphor layer 20 in the X-axis direction is substantially equal to the outer dimension W4 of the two light emitting elements 10 including the filling member 30A. By making the outer dimensions of the first phosphor layer 20 and the outer dimensions of the plurality of light emitting elements 10 substantially equal, the area of ​​the light emitting surface of the light emitting device 1 can be reduced. Therefore, the output light emitted from the light emitting device 1 is less likely to diffuse, and the output light is more likely to be taken in by a lens provided near the light emitting device 1. As a result, it is possible to reduce the size of the lens provided near the light emitting device 1. Furthermore, by making the lens smaller, the housing that holds the lens and the light emitting device 1 therein can also be made smaller.

[0035] In this specification, "the outer dimensions of the first phosphor layer 20 are substantially equal to the outer dimensions of the plurality of light-emitting elements 10" means that the difference between the outer dimensions of the first phosphor layer 20 and the outer dimensions of the plurality of light-emitting elements 10 is ±10% or less. Specifically, this means that the difference between the outer dimension W1 of the first phosphor layer 20 and the outer dimension W3 of the light-emitting element 10 is ±10%, and the difference between the outer dimension W2 of the first phosphor layer 20 and the outer dimension W4 of the light-emitting element 10 is ±10%. It is preferable that the difference between the outer dimensions of the first phosphor layer 20 and the outer dimension of the plurality of light-emitting elements 10 is ±5% or less.

[0036] The operation of the light emitting device 1 of this embodiment having such a configuration will be described. In the light emitting device 1 of this embodiment, first, when power is applied to the light emitting element 10, excitation light (primary light) is emitted upward from the light emitting element 10. The emitted excitation light passes through the first phosphor layer 20, and at this time, a part of the excitation light is absorbed by fluorescent ions of the phosphor contained in the first phosphor layer 20. Then, it is converted into fluorescence by electronic energy transition of the fluorescent ions, and the fluorescence is emitted upward from the phosphor.

[0037] Here, when absorbing the excitation light and converting the wavelength into fluorescence, the phosphor in the first phosphor layer 20 generates heat. However, the phosphor that mainly generates heat is the phosphor in the region that is mainly irradiated with the excitation light. That is, the phosphor that mainly generates heat is the phosphor in the region 22 surrounded by the dotted line in FIG. 2A and FIG. 2B, specifically, the phosphor located directly above the light-emitting element 10. In contrast, in the first phosphor layer 20, the phosphor that is not located directly above the light-emitting element 10, that is, the phosphor in the region 23 not surrounded by the dotted line in FIG. 2A and FIG. 2B, generates little or very little heat because it is irradiated with a small amount of excitation light. Therefore, as shown by the arrow in FIG. 2A and FIG. 2B, heat conduction occurs from the region 22 where the amount of heat is large to the region 23 where the amount of heat is small.

[0038] Filler 30A is located below region 23, which generates a small amount of heat, and upper surface 31A of filler 30A is in contact with region 23. Therefore, heat conducted to region 23 is conducted from region 23 to filler 30A, and heat conducted to filler 30A is conducted from filler 30A to substrate 40.

[0039] Furthermore, as described above, the first phosphor layer 20 is in contact with the upper surfaces 11 of the multiple light-emitting elements 10. Therefore, as shown by the arrows in Fig. 2A, heat generated in the region 22 of the first phosphor layer 20 is conducted from the first phosphor layer 20 to the light-emitting elements 10 below, and the heat conducted to the light-emitting elements 10 is further conducted from the light-emitting elements 10 to the substrate 40. The heat conducted to the substrate 40 is dissipated to the outside of the substrate 40.

[0040] Thus, in the light emitting device 1 of the present embodiment, heat generated in region 22 of first phosphor layer 20 is conducted to region 23 which is relatively low temperature, and then conducted from region 23 to filler member 30A, and then conducted to substrate 40. At the same time, heat generated in region 22 of first phosphor layer 20 is conducted to light emitting element 10, and then conducted from light emitting element 10 to substrate 40. Therefore, heat is efficiently dissipated in region 22 of first phosphor layer 20, and it is possible to suppress temperature quenching of the phosphor contained in region 22.

[0041] Here, if the filling member 30A located between adjacent light emitting elements 10 is not provided, an air layer will exist between the adjacent light emitting elements 10. However, since the air layer has low thermal conductivity, it becomes difficult to dissipate the heat conducted to the region 23. However, since the filling member 30A is provided in the light emitting device 1, it becomes possible to conduct the heat of the region 23 to the substrate 40 via the filling member 30A.

[0042] Moreover, if the light emitting element 10 and the first phosphor layer 20 are not in contact with each other and a gap exists between them, the excitation light emitted from the light emitting element 10 spreads and the excitation light is irradiated over the entire first phosphor layer 20. As a result, the entire first phosphor layer 20 generates heat, making it difficult to generate a relatively low-temperature region 23, and there is a possibility that the first phosphor layer 20 will not dissipate heat sufficiently. Therefore, in order to generate the relatively low-temperature region 23, the first phosphor layer 20 needs to be in contact with a plurality of light emitting elements 10.

[0043] In the light-emitting device 1 shown in FIG. 1A, the height of the filling member 30 covering the entire periphery of the light-emitting element 10 is approximately the same as the height of the plurality of light-emitting elements 10. Therefore, the side of the first phosphor layer 20 is not in contact with the filling member 30. However, this embodiment is not limited to such a configuration. For example, the height of the filling member 30 may be approximately the same as the height of the stack of the light-emitting element 10 and the first phosphor layer 20, and the side of the first phosphor layer 20 may be in contact with the filling member 30. In this way, since the side of the first phosphor layer 20 is covered with the filling member 30, the heat generated in the first phosphor layer 20 can be conducted to the filling member 30 and dissipated. Therefore, the heat dissipation property of the first phosphor layer 20 can be further improved.

[0044] Furthermore, in the light emitting device 1, when the light emitting surface side of the plurality of light emitting elements 10 is viewed in plan, the outer dimensions of the first phosphor layer 20 are substantially equal to the outer dimensions of the plurality of light emitting elements 10. Therefore, the output light emitted from the light emitting device 1 is less likely to diffuse, and the output light is more likely to be captured by a lens provided near the light emitting device 1, making it possible to miniaturize the lens.

[0045] [Second embodiment] Next, a light emitting device according to a second embodiment will be described in detail. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and duplicated descriptions will be omitted.

[0046] As shown in FIGS. 3A and 3B, the light emitting device 2 of this embodiment includes a plurality of light emitting elements 10 arranged at predetermined intervals, a first phosphor layer 20, and a filling member 30.

[0047] As in the first embodiment, a plurality of light emitting elements 10 are mounted on a flat substrate 40 and arranged in two rows in the X-axis direction and two rows in the Y-axis direction. Adjacent light emitting elements 10 are spaced apart from each other at a predetermined interval.

[0048] The first phosphor layer 20 is made of phosphor ceramics obtained by sintering a phosphor, and is a plate-like member covering the light emission surfaces of the plurality of light-emitting elements 10. The filling member 30 is disposed so as to be in contact with the periphery of each light-emitting element 10 and to cover the entire periphery of the light-emitting elements 10. The filling member 30 is also provided so as to fill the gaps between adjacent light-emitting elements 10. A dam material 50 serving as a side wall is provided on the outer periphery of the filling member 30 provided around the plurality of light-emitting elements 10.

[0049] The first phosphor layer 20 covers not only the light emission surfaces of the four light emitting elements 10, but also the upper surface of the filling member 30A located between adjacent light emitting elements 10. The first phosphor layer 20 may be laminated directly on the upper surface 11 of the plurality of light emitting elements 10, or may be laminated via an adhesive layer.

[0050] Here, the light emitting device 2 of this embodiment further includes a second phosphor layer 60 laminated on the first phosphor layer 20. As described in the first embodiment, in the light emitting device 2, the heat dissipation property of the first phosphor layer 20 is improved. Therefore, even if the second phosphor layer 60, which serves as a heat source, is laminated on the first phosphor layer 20, it is possible to suppress a rise in temperature of the first phosphor layer 20. Furthermore, by providing the second phosphor layer 60 in addition to the first phosphor layer 20, a light emitting device capable of emitting fluorescence of a plurality of wavelengths can be obtained.

[0051] The second phosphor layer 60 may be made of phosphor ceramics obtained by sintering a phosphor, or may be a wavelength conversion member in which phosphor particles are dispersed in a light-transmitting material such as silicone resin. However, the second phosphor layer 60 is preferably made of phosphor ceramics obtained by sintering a phosphor. This allows the heat generated from the phosphor in the second phosphor layer 60 to be efficiently dissipated, and temperature quenching of the phosphor can be suppressed.

[0052] The phosphor contained in the second phosphor layer 60 is not particularly limited, and at least one of a blue phosphor, a green phosphor, a yellow phosphor, a red phosphor, and a near-infrared phosphor can be used. Note that the blue phosphor, the green phosphor, the yellow phosphor, the red phosphor, and the near-infrared phosphor can be the ones described above.

[0053] In the light emitting device 2, the second phosphor layer 60 is laminated on the upper surface 24 of the first phosphor layer 20, and is a single plate-like member covering the upper surface 24 of the first phosphor layer 20. The second phosphor layer 60 may be laminated directly on the upper surface 24 of the first phosphor layer 20, or may be laminated via an adhesive layer. The adhesive layer for bonding the first phosphor layer 20 and the second phosphor layer 60 is not particularly limited, and at least one of an inorganic adhesive and an organic adhesive having optical transparency can be used, for example.

[0054] In the light emitting device 2, when the light emitting surface side of the plurality of light emitting elements 10 is viewed in plan, it is preferable that the outer dimensions of the second phosphor layer 60 are substantially equal to the outer dimensions of the first phosphor layer 20. Specifically, as shown in FIG. 3B, it is preferable that the outer dimension W1 of the first phosphor layer 20 in the Y-axis direction and the outer dimension W5 of the second phosphor layer 60 are substantially equal. Similarly, it is preferable that the outer dimension W2 of the first phosphor layer 20 in the X-axis direction and the outer dimension W6 of the second phosphor layer 60 are substantially equal. By making the outer dimensions of the first phosphor layer 20 and the outer dimensions of the second phosphor layer 60 substantially equal, the area of ​​the light emitting surface of the light emitting device 2 can be reduced. Therefore, the output light emitted from the light emitting device 2 is less likely to diffuse, and the output light is more likely to be captured by a lens provided in the vicinity of the light emitting device 2. As a result, it is possible to miniaturize the lens provided in the vicinity of the light emitting device 2. Furthermore, by making the lens smaller, the housing that holds the lens and the light emitting device 2 therein can also be made smaller.

[0055] In this specification, "the outer dimensions of the second phosphor layer 60 are substantially equal to those of the first phosphor layer 20" means that the difference between the outer dimensions of the second phosphor layer 60 and the outer dimensions of the first phosphor layer 20 is ±10% or less. Specifically, this means that the difference between the outer dimension W5 of the second phosphor layer 60 and the outer dimension W1 of the first phosphor layer 20 is ±10%, and the difference between the outer dimension W6 of the second phosphor layer 60 and the outer dimension W2 of the first phosphor layer 20 is ±10%. It is preferable that the difference between the outer dimensions of the second phosphor layer 60 and the outer dimension of the first phosphor layer 20 is ±5% or less.

[0056] The operation of the light emitting device 2 of this embodiment having such a configuration will be described. In the light emitting device 2 of this embodiment, first, when power is applied to the light emitting element 10, excitation light (primary light) is emitted upward from the light emitting element 10. The emitted excitation light passes through the first phosphor layer 20 and the second phosphor layer 60, and at this time, a part of the excitation light is absorbed by the fluorescent ions of the phosphor contained in the first phosphor layer 20. Similarly, a part of the excitation light is absorbed by the fluorescent ions of the phosphor contained in the second phosphor layer 60. Then, the fluorescent ions are converted into fluorescence by the electron energy transition, and the fluorescence is emitted upward from the phosphor. Note that the light emitting device 2 may be configured such that the fluorescence emitted from the phosphor of the first phosphor layer 20 is absorbed by the phosphor of the second phosphor layer 60, and fluorescence of a longer wavelength is emitted.

[0057] Here, when absorbing the excitation light and converting the wavelength into fluorescence, the phosphors of the first phosphor layer 20 and the second phosphor layer 60 generate heat. However, the phosphors that mainly generate heat are those in the region that is mainly irradiated with the excitation light. That is, the phosphors that mainly generate heat are those in the region 22A surrounded by the dotted line in FIG. 3A and FIG. 3B, specifically, those located directly above the light-emitting element 10. In contrast, in the first phosphor layer 20 and the second phosphor layer 60, phosphors that are not located directly above the light-emitting element 10, that is, those in the region 23A not surrounded by the dotted line in FIG. 3A and FIG. 3B, generate little or very little heat because they are irradiated with a small amount of excitation light. Therefore, as shown by the arrows in FIG. 3A and FIG. 3B, heat conduction occurs from the region 22A where the amount of heat is large to the region 23A where the amount of heat is small.

[0058] Filler 30A is located below region 23A, which generates a small amount of heat, and upper surface 31A of filler 30A is in contact with region 23A. Therefore, the heat conducted to region 23A is conducted from region 23A to filler 30A, and the heat conducted to filler 30A is further conducted from filler 30A to substrate 40.

[0059] Furthermore, as described above, the first phosphor layer 20 is in contact with the upper surfaces 11 of the multiple light-emitting elements 10. Therefore, as shown by the arrows in Fig. 3A, heat generated in the region 22A of the first phosphor layer 20 is conducted from the first phosphor layer 20 to the light-emitting elements 10 below, and the heat conducted to the light-emitting elements 10 is further conducted from the light-emitting elements 10 to the substrate 40. The heat conducted to the substrate 40 is dissipated to the outside of the substrate 40.

[0060] As described above, in the light emitting device 2 of the present embodiment, heat generated in the region 22A of the first phosphor layer 20 and the second phosphor layer 60 is conducted to the relatively low temperature region 23A, and then conducted from the region 23A to the filler member 30A, and then conducted to the substrate 40. At the same time, heat generated in the region 22A of the first phosphor layer 20 is conducted to the light emitting element 10, and then conducted from the light emitting element 10 to the substrate 40. Therefore, heat is efficiently dissipated in the region 22A of the first phosphor layer 20 and the second phosphor layer 60, and it is possible to suppress temperature quenching of the phosphors contained in the region 22A.

[0061] 3A, the height of the filling member 30 covering the entire periphery of the light emitting element 10 is approximately the same as the height of the multiple light emitting elements 10. Therefore, the side surface of the first phosphor layer 20 and the side surface of the second phosphor layer 60 are not in contact with the filling member 30. However, this embodiment is not limited to such a configuration.

[0062] As in the light-emitting device 3 shown in Fig. 4, the height of the filling member 30 may be substantially the same as the height of the laminate of the light-emitting element 10, the first phosphor layer 20, and the second phosphor layer 60, and the side surfaces of the first phosphor layer 20 and the second phosphor layer 60 may be in contact with the filling member 30. In this manner, the side surfaces of the first phosphor layer 20 and the second phosphor layer 60 are covered with the filling member 30, so that heat generated in the first phosphor layer 20 and the second phosphor layer 60 can be conducted to the filling member 30 and dissipated. Therefore, it is possible to further improve the heat dissipation properties of the first phosphor layer 20 and the second phosphor layer 60.

[0063] [Third embodiment] Next, a light emitting device according to a third embodiment will be described in detail. Note that the same components as those in the first and second embodiments are denoted by the same reference numerals, and duplicated descriptions will be omitted.

[0064] As shown in Fig. 5, the light emitting device 4 according to the third embodiment includes a plurality of light emitting elements 10 arranged at a predetermined interval, a first phosphor layer 20, and filling members 30, 30A. Similarly to the light emitting device 3 shown in Fig. 4, a second phosphor layer 60 is laminated on the first phosphor layer 20, and the side surfaces of the first phosphor layer 20 and the second phosphor layer 60 are covered with the filling member 30.

[0065] As described in the second embodiment, in the light emitting device 2, the heat dissipation properties of the first phosphor layer 20 and the second phosphor layer 60 are improved. Therefore, even if a phosphor layer 70 is further laminated on the second phosphor layer 60, it is possible to suppress a rise in temperature of the first phosphor layer 20 and the second phosphor layer 60. Furthermore, by providing another phosphor layer 70 in addition to the first phosphor layer 20 and the second phosphor layer 60, it is possible to obtain a light emitting device capable of emitting fluorescence of a plurality of wavelengths.

[0066] The third phosphor layer 70 may be made of phosphor ceramics obtained by sintering a phosphor, or may be a wavelength conversion member in which a phosphor is dispersed in a light-transmitting material. The light-transmitting material used in the wavelength conversion member may be a resin, for example, a silicone resin. The phosphor contained in the third phosphor layer 70 is not particularly limited, but at least one of a blue phosphor, a green phosphor, a yellow phosphor, a red phosphor, and a near-infrared phosphor may be used. The blue phosphor, the green phosphor, the yellow phosphor, the red phosphor, and the near-infrared phosphor may be the above-mentioned phosphors.

[0067] In the light emitting device 4, the third phosphor layer 70 is laminated on the upper surface 61 of the second phosphor layer 60, and is a single plate-like member covering the upper surface 61 of the second phosphor layer 60. The third phosphor layer 70 may be laminated directly on the upper surface 61 of the second phosphor layer 60, or may be laminated via an adhesive layer. The adhesive layer for bonding the second phosphor layer 60 and the third phosphor layer 70 is not particularly limited, and at least one of an inorganic adhesive and an organic adhesive having optical transparency can be used, for example.

[0068] The operation of the light emitting device 4 of this embodiment having such a configuration will be described. In the light emitting device 4 of this embodiment, first, when power is applied to the light emitting element 10, the light emitting element 10 emits excitation light (primary light) upward. The emitted excitation light passes through the first phosphor layer 20, the second phosphor layer 60, and the third phosphor layer 70, and at this time, a part of the excitation light is absorbed by the fluorescent ions of the phosphors contained in the first phosphor layer 20 and the second phosphor layer 60. Similarly, a part of the excitation light is absorbed by the fluorescent ions of the phosphors contained in the third phosphor layer 70. Then, the fluorescent ions are converted into fluorescence by the electron energy transition, and the fluorescence is emitted upward from the phosphors. Note that the light emitting device 4 may be configured such that the fluorescent emitted from the phosphors of the first phosphor layer 20 and / or the second phosphor layer 60 is absorbed by the phosphors of the third phosphor layer 70 to emit fluorescence of a longer wavelength.

[0069] In the light emitting device 4, the phosphor contained in the first phosphor layer 20 is a near infrared phosphor (Ga, Sc)2O3:Cr 3+ The phosphor contained in the second phosphor layer 60 is a near-infrared phosphor, Gd3Ga2(GaO4)3:Cr 3+ The phosphor contained in the third phosphor layer 70 is a red phosphor, CaAlSiN3:Eu 2+ By using such a phosphor, it is possible to obtain a light emitting device 4 capable of emitting near-infrared light and red light. Such a light emitting device 4 can be used as a light source for quality inspection of an object to be inspected, utilizing near-infrared light and red light.

[0070] In the light emitting device 4, the third phosphor layer 70 is preferably a wavelength conversion member in which phosphor particles are dispersed in a translucent resin. The refractive index of the translucent resin is intermediate between the refractive index of the second phosphor layer 60 made of phosphor ceramics and the refractive index of air. In other words, when the fluorescence transmitted through the second phosphor layer 60 is radiated to the outside of the light emitting device 4, the third phosphor layer 70 functions as an intermediate refractive index layer between the phosphor ceramics and air. Therefore, the light extraction efficiency from the light emitting device 4 can be improved.

[0071] (Additional Note) The above description of the embodiments discloses the following techniques.

[0072] (Technology 1) A light-emitting device comprising a plurality of light-emitting elements arranged at a predetermined interval, a first phosphor layer made of phosphor ceramics, and a filler member covering the side surfaces of the plurality of light-emitting elements and provided between adjacent light-emitting elements; A light-emitting device, wherein the first phosphor layer is a plate-shaped member covering the light emission surfaces of the plurality of light-emitting elements, and the first phosphor layer is arranged so as to abut the plurality of light-emitting elements and the filling member.

[0073] With this configuration, heat generated in region 22 of first phosphor layer 20 is conducted to region 23 of relatively low temperature, and then conducted from region 23 to filler member 30A, and then conducted to substrate 40. At the same time, heat generated in region 22 of first phosphor layer 20 is conducted to light emitting element 10, and then conducted from light emitting element 10 to substrate 40. Therefore, heat dissipation from first phosphor layer 20 is performed efficiently, making it possible to suppress temperature quenching of the phosphor.

[0074] (Technology 2) The light emitting device according to Technology 1, wherein, in a plan view of the light emitting surface sides of the plurality of light emitting elements, the outer dimensions of the first phosphor layer are substantially equal to the outer dimensions of the plurality of light emitting elements.

[0075] This configuration makes it difficult for the output light emitted from the light emitting device to diffuse. Therefore, the output light is easily captured by a lens provided near the light emitting device, making it possible to miniaturize the lens. Furthermore, by miniaturizing the lens, the housing that holds the lens and the light emitting device inside can also be miniaturized.

[0076] (Technology 3) The light emitting device according to Technology 1 or 2, further comprising a second phosphor layer laminated on the first phosphor layer.

[0077] In the light emitting device of this embodiment, the heat dissipation property of the first phosphor layer 20 is improved, so that even if the second phosphor layer 60 is further laminated on the first phosphor layer 20, it is possible to suppress a temperature rise of the first phosphor layer 20. Furthermore, by providing the second phosphor layer 60 in addition to the first phosphor layer 20, a light emitting device that emits fluorescence of a plurality of wavelengths can be obtained.

[0078] (Technique 4) The light emitting device according to Technique 3, wherein the second phosphor layer is made of phosphor ceramics.

[0079] This configuration makes it possible to efficiently dissipate heat generated from the phosphors in the second phosphor layer 60 and to suppress temperature quenching of the phosphors.

[0080] (Technology 5) The light emitting device according to Technology 3 or 4, wherein, when viewed in plan from the light emission surface side of the plurality of light emitting elements, the outer dimensions of the second phosphor layer are substantially equal to the outer dimensions of the first phosphor layer.

[0081] This configuration makes it difficult for the output light emitted from the light emitting device to diffuse. Therefore, the output light is easily captured by a lens provided near the light emitting device, making it possible to miniaturize the lens. Furthermore, by miniaturizing the lens, the housing that holds the lens and the light emitting device inside can also be miniaturized.

[0082] (Technique 6) The light emitting device according to any one of Techniques 3 to 5, wherein the second phosphor layer is adhered to the first phosphor layer.

[0083] With this configuration, the first phosphor layer 20 and the second phosphor layer 60 are bonded to each other, and the interface between the first phosphor layer 20 and the second phosphor layer 60 can be tightly attached. Therefore, heat conduction between the first phosphor layer 20 and the second phosphor layer 60 is easily generated, and the heat dissipation properties of the first phosphor layer 20 and the second phosphor layer 60 can be improved.

[0084] (Technique 7) The light emitting device according to any one of Techniques 3 to 6, wherein a side surface of the first phosphor layer and a side surface of the second phosphor layer are covered with the filling member.

[0085] With this configuration, heat generated in the first phosphor layer 20 and the second phosphor layer 60 can be dissipated by being conducted to the filling member 30. Therefore, it is possible to further improve the heat dissipation properties of the first phosphor layer 20 and the second phosphor layer 60.

[0086] (Technology 8) The light emitting device according to any one of Technologies 1 to 7, wherein the filling member includes a reflective material that reflects light.

[0087] With this configuration, the excitation light emitted from the light emitting element 10 and the fluorescence emitted from the phosphor are reflected, so that the spread of the light radiated from the light emitting element 10, the first phosphor layer 20, and the second phosphor layer 60 can be suppressed, and the leakage of light can be reduced. Therefore, the light emitting efficiency of the light emitting device can be improved.

[0088] (Technique 9) The light emitting device according to any one of Techniques 3 to 8, further comprising one or more phosphor layers laminated on the second phosphor layer.

[0089] In the light emitting device of this embodiment, the heat dissipation properties of the first phosphor layer 20 and the second phosphor layer 60 are improved, so that even if a phosphor layer 70 is further laminated on the second phosphor layer 60, it is possible to suppress a rise in temperature of the first phosphor layer 20 and the second phosphor layer 60. Furthermore, by providing another phosphor layer 70 in addition to the first phosphor layer 20 and the second phosphor layer 60, a light emitting device that emits fluorescence of multiple wavelengths can be obtained.

[0090] (Technique 10) Further comprising a third phosphor layer laminated on the second phosphor layer, The light emitting device according to any one of techniques 3 to 9, wherein the third phosphor layer contains phosphor particles and a resin in which the phosphor particles are dispersed.

[0091] This configuration makes it possible to obtain a light-emitting device that emits fluorescence of multiple wavelengths. Furthermore, since the third phosphor layer 70 functions as an intermediate refractive index layer between the phosphor ceramics and air, it is possible to improve the light extraction efficiency from the light-emitting device. EXAMPLES

[0092] The present embodiment will be described in more detail below with reference to examples and comparative examples, but the present embodiment is not limited to these examples.

[0093] [Example 1] (Preparation of the first phosphor layer) First, a synthesis method utilizing a solid-state reaction was used to synthesize a first phosphor layer to be used in a light-emitting device. The first phosphor constituting the first phosphor layer is a near-infrared phosphor, (Ga 0.59 Cr 0.01 Sc 0.4 In this specification, the oxide phosphor is represented by the composition formula (Ga,Sc)2O3:Cr 3+ The phosphor is also called "GaSc phosphor."

[0094] In synthesizing the first phosphor layer, the following compound powders were used as main raw materials. Gallium oxide (Ga2O3): 4N purity, Asia Physical Materials Co., Ltd. Chromium trioxide (Cr2O3): 3N purity, High Purity Chemical Laboratory Co., Ltd. Scandium oxide (Sc2O3): Purity > 3N, High Purity Chemical Laboratory Co., Ltd.

[0095] In order to enhance the reactivity between the raw materials, the following compound powders were used as reaction accelerators. Boric acid (H3BO3): Fujifilm Wako Pure Chemical Corporation

[0096] First, the stoichiometric compound (Ga 0.59 Cr 0.01 Sc 0.4 The raw materials were weighed out so that the desired compound ((Ga 0.59 Cr 0.01 Sc 0.4 The reaction accelerator was weighed out so that the molar ratio of the raw materials to the reaction accelerator was 3%. Next, the weighed raw materials and the reaction accelerator were placed in a cylindrical container, and an appropriate amount of pure water was poured in. After that, the container containing the raw materials, the reaction accelerator, and the pure water was set in a planetary mill (PULVERISETTE5, manufactured by Fritsch Japan Co., Ltd.), and the raw materials and the reaction accelerator were thoroughly wet-mixed. The rotation speed of the planetary mill was 200 rpm, and the mixing time was 30 minutes.

[0097] Next, the slurry-like mixed raw material containing each raw material, reaction accelerator, and pure water was transferred to a metal container lined with a Naflon (registered trademark) sheet, and dried at 150°C for about 3 hours using a dryer to evaporate the pure water. The dried mixed raw material was then lightly crushed using a mortar and pestle. After that, coarse particles were removed from the crushed mixed raw material using a mesh with an opening of about 512 μm. In this way, the mixed raw material for the first phosphor layer was obtained.

[0098] Next, the mixed raw material of the first phosphor layer was molded into a thin cylindrical shape using a manual hydraulic press (manufactured by Riken Seiki Co., Ltd.) and a cylindrical mold (φ13 mm). The pressure applied to the pressure-receiving surface of the sample during molding was about 20 MPa. In this way, a molded body of the mixed raw material was obtained.

[0099] Next, the molded body of the mixed raw material was sintered in a box-shaped atmospheric furnace at a processing temperature of 1400° C. for 4 hours. In this way, a sintered body of the mixed raw material was obtained.

[0100] Then, the top and bottom surfaces of the sintered body were polished using a polishing machine (DFD6340, manufactured by Disco Corporation). The polishing blade used for polishing was #1400. The thickness of the sintered body after polishing was about 100 μm. Next, the polished sintered body was diced into a thin rectangular parallelepiped shape using a dicing machine (DAD3350, manufactured by Disco Corporation). The outer diameter size in a plan view after dicing was about 3.3 mm in length and about 2.6 mm in width. In this way, (Ga,Sc)2O3:Cr 3+ The resultant was sintered to obtain a first phosphor layer.

[0101] (Preparation of the second phosphor layer) Next, a synthesis method using a solid-state reaction was used to synthesize a second phosphor layer to be used in a light-emitting device. The second phosphor constituting the second phosphor layer is a near-infrared phosphor, Gd3(Ga 0.97 Cr 0.03 )2Ga3O 12 In this specification, Gd3Ga2Ga3O 12 :Cr 3+ The phosphor is also called a "GGG phosphor."

[0102] In synthesizing the second phosphor layer, the following compound powders were used as main raw materials. Gadolinium oxide (Gd2O3): 4N purity, Japan Yttrium Co., Ltd. Gallium oxide (Ga2O3): 4N purity, Asia Physical Materials Co., Ltd. Chromium trioxide (Cr2O3): 3N purity, High Purity Chemical Laboratory Co., Ltd.

[0103] First, the stoichiometric compound Gd3(Ga 0.97 Cr 0.03 )2Ga3O 12 The raw materials were weighed so that the weight of each raw material was 100g. Next, the weighed raw materials and reaction accelerator were put into a cylindrical container, and an appropriate amount of ethanol was further poured in. After that, the container containing each raw material, reaction accelerator, and ethanol was set in a planetary mill (PULVERISETTE5, manufactured by Fritsch Japan Co., Ltd.), and each raw material and reaction accelerator were thoroughly wet-mixed. The rotation speed of the planetary mill was 200 rpm, and the mixing time was 30 minutes.

[0104] Next, the slurry-like mixed raw material containing each raw material, reaction accelerator, and ethanol was transferred to a metal container lined with a Naflon sheet, and dried using a dryer at 125°C for about 2 hours to evaporate the ethanol. The dried mixed raw material was then lightly crushed using a mortar and pestle. After that, coarse particles were removed from the crushed mixed raw material using a mesh with an opening of about 516 μm. In this way, the mixed raw material for the second phosphor layer was obtained.

[0105] Next, the mixed raw material of the second phosphor layer was molded into a thin cylindrical shape using a manual hydraulic press (manufactured by Riken Seiki Co., Ltd.) and a cylindrical mold (φ13 mm). The pressure applied to the pressure-receiving surface of the sample during molding was about 20 MPa. In this way, a molded body of the mixed raw material was obtained.

[0106] Next, the molded body of the mixed raw material was sintered using a Tammann tube type atmosphere electric furnace. The sintering atmosphere was nitrogen, the treatment temperature was 1600°C, and the treatment time was 2 hours. In this way, a sintered body of the mixed raw material was obtained.

[0107] Then, the top and bottom surfaces of the sintered body were polished using a polishing machine (DISCO Corporation, DFD6340). The polishing blade used for polishing was #1400. The thickness of the sintered body after polishing was about 100 μm. Next, the polished sintered body was diced into a thin rectangular parallelepiped shape using a dicing machine (DISCO Corporation, DAD3350). The outer diameter size in a plan view after dicing was about 3.3 mm in length and about 2.6 mm in width. In this way, Gd3Ga2Ga3O 12 :Cr 3+ The resultant was sintered to obtain a second phosphor layer.

[0108] (Density Measurement of the First Phosphor Layer and the Second Phosphor Layer) The densities of the first phosphor layer and the second phosphor layer obtained as described above were measured. Specifically, the weight and volume of the first phosphor layer were measured, and the measured weight was divided by the measured volume to evaluate the density of the first phosphor layer. As a result of the evaluation, the density of the first phosphor layer was 4.59 g / cm 3 The density of the second phosphor layer was evaluated by the Archimedes method. As a result of the evaluation, the density of the second phosphor layer was 6.94 g / cm 3 It was.

[0109] (Calculation of Thermal Conductivity of First Phosphor Layer and Second Phosphor Layer) The specific heat capacity and thermal diffusivity of the first phosphor layer and the second phosphor layer were evaluated using a xenon flash analyzer (LFA447, Netzsch Japan Co., Ltd.). As a result of the evaluation, the specific heat capacities of the first phosphor layer and the second phosphor layer were 0.561 J / g / K and 0.352 J / g / K, respectively. The thermal diffusivities of the first phosphor layer and the second phosphor layer were 3.36 mm 2 / s, 2.67mm 2 / s.

[0110] Since thermal conductivity is the product of density, specific heat capacity, and thermal diffusivity, the thermal conductivity of the first phosphor layer and the second phosphor layer was calculated using this formula, and the thermal conductivity of the first phosphor layer and the second phosphor layer was found to be 8.64 J / s / m / K and 6.52 J / s / m / K, respectively.

[0111] (Fabrication of light-emitting device) A light-emitting device was fabricated using the first and second phosphor layers obtained as described above. First, a commercially available multi-chip LED package including a substrate, four blue LEDs, and a dam material was prepared.

[0112] The four blue LEDs are mounted on a substrate and arranged in two rows in the X-axis direction and two rows in the Y-axis direction, as shown in Figure 1C. Adjacent blue LEDs are arranged with a certain distance between them. The outer diameter of each blue LED is approximately 1.2 mm x 1.5 mm, and the distance between adjacent blue LEDs is approximately 0.15 mm. The outer diameter of the four blue LEDs is approximately 2.6 x 3.2 mm.

[0113] The dam material is placed all around the four blue LEDs, as shown in Figure 1C.

[0114] Next, a filler material was formed by applying and curing a white resin as a filler material between the four blue LEDs and the dam material in the multi-chip LED package, and between adjacent blue LEDs. The white resin used was LED silicone KER-2016WC-A / B manufactured by Shin-Etsu Chemical Co., Ltd.

[0115] Next, the first phosphor layer was attached onto the blue LED using an adhesive, LED silicone KER-2600-A / B manufactured by Shin-Etsu Chemical Co., Ltd.

[0116] In this way, the light emitting device of Example 1-1 having the first phosphor layer was obtained as shown in Figures 1A and 1B. In this example, the height of the filler was adjusted so that the side of the first phosphor layer was in contact with the filler. In the light emitting device of Example 1-1, the difference in the outer dimensions of the four blue LEDs with respect to the outer dimensions of the first phosphor layer was 5% or less.

[0117] Furthermore, a second phosphor layer was adhered onto the first phosphor layer in the light emitting device of Example 1-1. LED silicone KER-2600-A / B manufactured by Shin-Etsu Chemical Co., Ltd. was used as the adhesive.

[0118] In this way, as shown in FIG. 4, a light emitting device of Example 1-2 having a first phosphor layer and a second phosphor layer was obtained. In this example, the height of the filler was adjusted so that the side surfaces of the first phosphor layer and the second phosphor layer were in contact with the filler. In addition, in the light emitting device of Example 1-2, the difference in the outer dimensions of the four blue LEDs from the outer dimensions of the first phosphor layer was 5% or less. Furthermore, the difference in the outer dimensions of the first phosphor layer from the outer dimensions of the second phosphor layer was 5% or less.

[0119] (Beam profile of light emitting device) A beam profiler was used to measure the emission intensity distribution of the light emitted from the light emitting devices of Examples 1-1 and 1-2. Figure 6 shows the emission intensity distribution of the light emitting device of Example 1-1, and Figure 7 shows the emission intensity distribution of the light emitting device of Example 1-2. Note that since the near-infrared phosphors in the first phosphor layer and the second phosphor layer absorb blue light and convert it into near-infrared light, the areas with high emission intensity can be considered as areas that generate a lot of heat.

[0120] As shown in Figure 6, in the light emitting device of Example 1-1, the area directly above the blue LED has a high emission intensity and generates a lot of heat. In contrast, the area between the blue LEDs has a low emission intensity and generates little heat. Furthermore, it is also found that the area near the side of the first phosphor layer has a low emission intensity and generates little heat.

[0121] As shown in Figure 7, the light emitting device of Example 1-2 also has a high emission intensity and generates a lot of heat in the area directly above the blue LED. In contrast, the area between the blue LEDs has a low emission intensity and generates little heat. Furthermore, it is also found that the area near the side of the second phosphor layer has a low emission intensity and generates little heat.

[0122] [Example 2] Next, CAE (Computer Aided Engineering) analysis was performed on the temperature distribution of the first phosphor layer and the second phosphor layer in the light emitting devices of Examples 2-1 to 2-3 and Comparative Examples 2-1 to 2-3.

[0123] (Analysis model) Fig. 8 shows the overall shape of the analysis model used in the CAE analysis, and Fig. 9, Fig. 10A and Fig. 10B show schematic diagrams of the light-emitting module. As shown in Fig. 8, the CAE analysis set a spherical region of Φ450 mm consisting of air as the surrounding region 100. In this case, the origin was set to the center of the surrounding region 100, and the direction of gravity was set to the -Z direction. Note that this spherical region is assumed to be an integrating sphere. The light-emitting module 110 was then placed so that the light-emitting portion (light-emitting element) was located at the center of the surrounding region 100.

[0124] The light emitting module 110 includes an aluminum base 111, a heat sink 112, and a fan 113. The light emitting module 110 does not include a lens or a cylindrical housing. The light emitting module 110 is disposed so that the light is emitted upward (Z direction).

[0125] Aluminum base 111 is made of aluminum, and has a countersunk 111a formed on its upper surface to hold light emitting device 1. The size of aluminum base 111 is 55 mm in length (X direction), 55 mm in width (Y direction), and 10 mm in height (Z direction), and the depth of the countersunk is 2 mm. The thermal conductivity of aluminum base 111 is set to 138 W / m·K.

[0126] The heat sink 112 had an aluminum base 111 disposed on the upper surface thereof, and had a size of 59 mm in length, 59 mm in width, and 30 mm in height. The thermal conductivity of the heat sink 112 was set to 180 W / m·K.

[0127] Fan 113 is cylindrical, and has heat sink 112 disposed on the upper surface. Fan 113 has a size of Φ55 mm and a height of 25 mm. Fan 113 was set to generate only an upward wind with a wind speed of 2 m / s.

[0128] A contact thermal resistance simulating a TIM (Thermal Interface Material) was set between the light emitting device 1 and the aluminum base 111, and between the aluminum base 111 and the heat sink 112. The contact thermal resistance had a thickness of 300 μm and a thermal conductivity of 1.5 W / m·K.

[0129] 10A and 11, the light emitting device 1 includes a plurality of light emitting elements 10, a first phosphor layer 20, a second phosphor layer 60, a third phosphor layer 70, filling members 30, 30A, a substrate 40, and a dam material 50. The light emitting elements 10 are LEDs in which GaN and Si3N4 are laminated. The GaN has a thickness of 10 μm, a thermal conductivity of 160 W / m·K, and a heat generation amount of 22.07 W. The Si3N4 has a thickness of 90 μm and a thermal conductivity of 85 W / m·K.

[0130] The first phosphor layer 20 was made of phosphor ceramics made of GaSc phosphor, with a thickness of 100 μm, a thermal conductivity of 8.6 W / m·K, and a heat generation amount of 8.00 W. The second phosphor layer 60 was made of phosphor ceramics made of GGG phosphor, with a thickness of 100 μm, a thermal conductivity of 6.5 W / m·K, and a heat generation amount of 1.84 W. The third phosphor layer 70 was made of CASN paste in which CASN was dispersed in silicone resin, with a thickness of 120 μm, a thermal conductivity of 0.2 W / m·K, and a heat generation amount of 0.72 W.

[0131] A contact thermal resistance simulating an adhesive was set between the substrate 40 and the light emitting element 10, and the contact thermal resistance had a thickness of 20 μm and a thermal conductivity of 57 W / m·K. A contact thermal resistance simulating an adhesive was also set between the light emitting element 10 and the first phosphor layer 20, and the contact thermal resistance had a thickness of 10 μm and a thermal conductivity of 0.2 W / m·K. A contact thermal resistance simulating an adhesive was also set between the first phosphor layer 20 and the second phosphor layer 60, and the contact thermal resistance had a thickness of 10 μm and a thermal conductivity of 0.2 W / m·K.

[0132] The filling members 30, 30A had a thickness of 0.42 mm and a thermal conductivity of 0.2 W / m·K. The dam material 50 had a length (X direction) of 9 mm, a width (Y direction) of 10 mm, a height (Z direction) of 0.4 mm, and a width of 1 mm, and a thermal conductivity of 0.2 W / m·K. The substrate 40 was made of a copper substrate and had dimensions of 15.5 mm in length (X direction), 27 mm in width (Y direction), and 1.5 mm in height (Z direction). The thermal conductivity of the substrate 40 was set to 398 W / m·K.

[0133] FIG. 12 shows the arrangement of four light-emitting elements 10 and dam materials 50 mounted on a substrate 40. As shown in FIG. 12, the four light-emitting elements 10 are arranged in two rows in the X-axis direction and two rows in the Y-axis direction, and the dam materials 50 are provided all around the light-emitting elements. Adjacent light-emitting elements 10 are arranged at a predetermined interval. The four light-emitting elements 10 have an outer dimension of 3.2 mm in the Y-axis direction and an outer dimension of 2.6 mm in the X-axis direction. The dimensions of one light-emitting element 10 are 1.525 mm×1.225 mm, and the interval between adjacent light-emitting elements is 0.15 mm.

[0134] 13 shows a state in which filling members 30, 30A are provided between the four light-emitting elements 10 and the dam material 50, and phosphor layers (first phosphor layer, second phosphor layer) are further laminated on the four light-emitting elements 10. The phosphor layers have an outer dimension of 3.2 mm in the Y-axis direction and an outer dimension of 2.6 mm in the X-axis direction. In the analysis model of FIG. 13, only the phosphor layers located directly above the light-emitting elements 10 are considered to be heat-generating regions, and the phosphor layers not located directly above the light-emitting elements 10 are considered to be non-heat-generating regions.

[0135] The components and set values ​​of the analysis model of Example 2 are summarized in Table 1, and the set values ​​of the contact resistance between the components are summarized in Table 2. The analysis conditions other than the set values ​​in Tables 1 and 2 were as follows: the ambient temperature of the surrounding area 100 was 30° C., the wind speed of the fan 113 was 2.0 m / s, the wind direction was +Z direction, and gravity was -Z direction. The CAE analysis was a steady analysis, and the number of cycles was 1000.

[0136] [Table 1]

[0137] [Table 2]

[0138] (Structures of Light-Emitting Devices of Examples 2-1 to 2-3 and Comparative Examples 2-1 to 2-3) FIG. 14 shows the structures of the light emitting devices of Examples 2-1 to 2-3 and Comparative Examples 2-1 to 2-3 that were subjected to CAE analysis. The light emitting device of Example 2-1 includes a light emitting element 10, a first phosphor layer 20, filling members 30 and 30A, a substrate 40, and a dam material 50. The light emitting devices of Examples 2-2 and 2-3 include a light emitting element 10, a first phosphor layer 20, a second phosphor layer 60, filling members 30 and 30A, a substrate 40, and a dam material 50. In the light emitting device of Example 2-2, the second phosphor layer 60 located directly above the light emitting element 10 is set as a heat generating portion. In the light emitting device of Example 2-3, the entire surface of the second phosphor layer 60 is set as a heat generating portion.

[0139] The light-emitting element of Comparative Example 2-1 includes a light-emitting element 10, a first phosphor layer 20, filling members 30 and 30A, a substrate 40, and a dam material 50, similar to Example 2-1. However, as shown in Fig. 14, the first phosphor layer 20 is not a single plate-like member but is divided into four pieces, and is further laminated only directly above the four light-emitting elements 10. Therefore, the filling member 30A is filled between adjacent light-emitting elements 10 and adjacent first phosphor layers 20.

[0140] The light emitting device of Comparative Example 2-2 includes a light emitting element 10, a first phosphor layer 20, a second phosphor layer 60, filling members 30 and 30A, a substrate 40, and a dam material 50. However, as shown in FIG. 14, the first phosphor layer 20 is not a single plate-like member but is divided into four, and is further stacked only directly above the four light emitting elements 10. Similarly, the second phosphor layer 60 is not a single plate-like member but is divided into four, and is further stacked only directly above the four light emitting elements. Therefore, the filling member 30A is filled between adjacent light emitting elements 10, between adjacent first phosphor layers 20, and between adjacent second phosphor layers 60.

[0141] The light emitting device of Comparative Example 2-3 includes a light emitting element 10, a first phosphor layer 20, a substrate 40, and a dam material 50. That is, the light emitting device of Comparative Example 2-3 has a configuration in which the filler members 30, 30A are removed from the light emitting device of Example 2-1.

[0142] (CAE analysis results) FIG. 14 shows the results of CAE analysis, specifically, the temperatures of the surfaces of the first phosphor layer 20 and the second phosphor layer 60 on the light-emitting surface side in each of the examples and comparative examples. FIG. 15 shows the temperature distribution (contour diagram) of the surface of the first phosphor layer 20 on the light-emitting surface side in the light-emitting devices of Example 2-1, Comparative Example 2-1, and Comparative Example 2-3. In Comparative Example 2-1 of FIG. 15, in addition to the first phosphor layer, the temperature distribution of the filler material present between the first phosphor layers is also shown. Furthermore, FIG. 16 shows the results of plotting the temperature on the diagonal line of the first phosphor layer in the temperature distribution of FIG. 15. Specifically, FIG. 16 shows the relationship between the diagonal distance and the surface temperature of the first phosphor layer 20 along the dotted line in FIG. 15.

[0143] 16, it can be seen that the surface temperature of the first phosphor layer 20 is lower overall in the light emitting device of Example 2-1 compared to the light emitting device of Comparative Example 2-3 that does not have a filler member. It can also be seen that the surface temperature of the light emitting device of Comparative Example 2-1 is low within a diagonal distance of 2 to 2.2 mm where the filler member is present, but the surface temperature of other parts is higher than that of the light emitting device of Example 2-1.

[0144] In this way, by forming the first phosphor layer as a single plate-like member and arranging the first phosphor layer so as to abut against the plurality of light-emitting elements and the filling member, heat is conducted toward the region 23 generating less heat and the filling member 30A. As a result, it is found that heat is efficiently dissipated from the first phosphor layer.

[0145] Fig. 17 shows the results of the CAE analysis, specifically, the temperature distribution (contour diagram) of the surfaces on the light emission surface side of the first phosphor layer 20 and the second phosphor layer 60 in the light emitting devices of Example 2-2, Example 2-3, and Comparative Example 2-2. In Comparative Example 2-2 of Fig. 17, in addition to the first phosphor layer, the temperature distribution of the filler material present between the first phosphor layers is also shown. Similarly, in Comparative Example 2-2 of Fig. 17, in addition to the second phosphor layer, the temperature distribution of the filler material present between the second phosphor layers is also shown.

[0146] Fig. 18 shows the results of plotting the temperatures on the diagonal line of the first phosphor layer in the temperature distribution of Fig. 17. Specifically, Fig. 18 shows the relationship between the diagonal distance and the surface temperature of the first phosphor layer 20 along the dotted line in Fig. 17. Fig. 19 shows the results of plotting the temperatures on the diagonal line of the second phosphor layer in the temperature distribution of Fig. 17. Specifically, Fig. 19 shows the relationship between the diagonal distance and the surface temperature of the second phosphor layer 60 along the dotted line in Fig. 17.

[0147] As shown in Fig. 18, the light emitting device of Comparative Example 2-2 has a low surface temperature between diagonal distances of 2 to 2.2 mm where the first phosphor layer is not present and the filling member is present, but the surface temperature of other parts is higher than that of the light emitting device of Example 2-2. In particular, the light emitting device of Example 2-2 has a significantly lower surface temperature between diagonal distances of 1 to 3 mm than that of the light emitting device of Comparative Example 2-2. Also, the light emitting device of Example 2-3 has a lower surface temperature between diagonal distances of 1 to 3 mm than that of the light emitting device of Comparative Example 2-2.

[0148] 19, the light emitting device of Comparative Example 2-2 has a lower surface temperature between diagonal distances of 2 to 2.2 mm where the second phosphor layer is not present and the filler member is present, but the surface temperature is higher overall than that of the light emitting device of Example 2-2. In particular, the light emitting device of Example 2-2 has a significantly lower surface temperature than the light emitting device of Comparative Example 2-2 between diagonal distances of 1 to 3 mm. Also, the light emitting device of Example 2-2 has a lower surface temperature than the light emitting device of Comparative Example 2-2 between diagonal distances of 1 to 3 mm.

[0149] In this way, by forming the first phosphor layer and the second phosphor layer as a single plate-like member and arranging the first phosphor layer so as to abut against the plurality of light-emitting elements and the filling member, heat is conducted toward the region 23A generating less heat and the filling member 30A. As a result, it is found that heat is efficiently dissipated from the first phosphor layer and the second phosphor layer.

[0150] Furthermore, from the results of the CAE analysis in Figure 15, the average value of the decrease in the surface temperature of the first phosphor layer and the maximum extent of the decrease in the surface temperature of the first phosphor layer were determined for the light-emitting device of Example 2-1 and the light-emitting devices of Comparative Example 2-1 and Comparative Example 2-3.

[0151] As shown in Table 3, when the diagonal distance of the first phosphor layer was in the ranges of 1.01 to 1.91 mm and 2.25 to 3.14 mm, the surface temperature of the first phosphor layer of the light emitting device of Example 2-1 was lower by an average of 2.5°C than that of the light emitting device of Comparative Example 2-1. Furthermore, when the diagonal distance was in the ranges of 1.01 to 1.91 mm and 2.25 to 3.14 mm, the surface temperature of the first phosphor layer of the light emitting device of Example 2-1 was lower by an average of 6.3°C than that of the light emitting device of Comparative Example 2-3.

[0152] Even in the entire range of diagonal distances from 0.00 to 4.04 mm, the light emitting device of Example 2-1 had an average temperature 1.1°C lower than that of Comparative Example 2-1, and the light emitting device of Example 2-1 had an average temperature 7.2°C lower than that of Comparative Example 2-3. The maximum difference in surface temperature of the first phosphor layer between the light emitting device of Example 2-1 and the light emitting device of Comparative Example 2-1 was 6.9°C. The maximum difference in surface temperature of the first phosphor layer between the light emitting device of Example 2-1 and the light emitting device of Comparative Example 2-3 was 26.2°C.

[0153] In this way, by making the first phosphor layer into a single plate-shaped member and arranging the first phosphor layer so that it abuts against multiple light-emitting elements and the filling member, it can be seen that heat is efficiently dissipated from the entire first phosphor layer.

[0154] [Table 3]

[0155] In addition, the average value of the decrease in the surface temperature of the first phosphor layer and the maximum extent of the decrease in the surface temperature of the first phosphor layer were obtained for the light emitting device of Example 2-2 and the light emitting device of Comparative Example 2-2 from the results of the CAE analysis in Fig. 17. Similarly, the average value of the decrease in the surface temperature of the second phosphor layer and the maximum extent of the decrease in the surface temperature of the second phosphor layer were also obtained.

[0156] As shown in Table 3, when the diagonal distance of the first phosphor layer was in the range of 1.01 to 1.91 mm and 2.25 to 3.14 mm, the surface temperature of the first phosphor layer of the light emitting device of Example 2-2 was lower by an average of 4.5°C than that of the light emitting device of Comparative Example 2-2. Also, in the entire range of diagonal distance of 0.00 to 4.04 mm, the surface temperature of the first phosphor layer of the light emitting device of Example 2-2 was lower by an average of 2.3°C than that of the light emitting device of Comparative Example 2-2. The maximum difference in surface temperature of the first phosphor layer between the light emitting device of Example 2-2 and the light emitting device of Comparative Example 2-2 was 8.6°C.

[0157] When the diagonal distance of the second phosphor layer was in the range of 1.01 to 1.91 mm and 2.25 to 3.14 mm, the surface temperature of the second phosphor layer of the light emitting device of Example 2-2 was lower by an average of 4.7°C than that of the light emitting device of Comparative Example 2-2. Also, in the entire range of diagonal distance of 0.00 to 4.04 mm, the surface temperature of the second phosphor layer of the light emitting device of Example 2-2 was lower by an average of 2.8°C than that of the light emitting device of Comparative Example 2-2. The maximum difference in the surface temperature of the second phosphor layer between the light emitting device of Example 2-2 and the light emitting device of Comparative Example 2-2 was 9.6°C.

[0158] Furthermore, from the results of the CAE analysis in Fig. 17, the average value of the decrease in the surface temperature of the first phosphor layer and the maximum extent of the decrease in the surface temperature of the first phosphor layer were obtained for the light emitting device of Example 2-3 and the light emitting device of Comparative Example 2-2. Similarly, the average value of the decrease in the surface temperature of the second phosphor layer and the maximum extent of the decrease in the surface temperature of the second phosphor layer were also obtained.

[0159] As shown in Table 3, when the diagonal distance of the first phosphor layer was in the range of 1.01 to 1.91 mm and 2.25 to 3.14 mm, the surface temperature of the first phosphor layer of the light emitting device of Example 2-3 was lower by an average of 3.3°C than that of the light emitting device of Comparative Example 2-2. Also, in the entire range of diagonal distance from 0.00 to 4.04 mm, the surface temperature of the first phosphor layer of the light emitting device of Example 2-3 was lower by an average of 2.2°C than that of the light emitting device of Comparative Example 2-2. The maximum difference in surface temperature of the first phosphor layer between the light emitting device of Example 2-3 and the light emitting device of Comparative Example 2-2 was 3.7°C.

[0160] When the diagonal distance of the second phosphor layer was in the range of 1.01 to 1.91 mm and 2.25 to 3.14 mm, the surface temperature of the second phosphor layer of the light emitting device of Example 2-3 was lower by an average of 3.5°C than that of the light emitting device of Comparative Example 2-2. Also, in the entire range of diagonal distance of 0.00 to 4.04 mm, the surface temperature of the second phosphor layer of the light emitting device of Example 2-3 was lower by an average of 2.8°C than that of the light emitting device of Comparative Example 2-2. The maximum difference in surface temperature of the second phosphor layer between the light emitting device of Example 2-3 and the light emitting device of Comparative Example 2-2 was 3.8°C.

[0161] In this way, by making the first phosphor layer and the second phosphor layer into a single plate-shaped member and arranging the first phosphor layer so that it abuts against a plurality of light-emitting elements and the filling member, it can be seen that heat is efficiently dissipated from the entire first phosphor layer and the second phosphor layer.

[0162] Although the present embodiment has been described above, the present embodiment is not limited to this, and various modifications are possible within the scope of the gist of the present embodiment. [Explanation of symbols]

[0163] 1,2,3,4 Light emitting device 10 Light emitting element 20 First phosphor layer 30,30A Filling material 60 Second phosphor layer 70 Third phosphor layer

Claims

1. A plurality of light emitting elements arranged at predetermined intervals; a first phosphor layer made of phosphor ceramics; A filler member covering side surfaces of the plurality of light emitting elements and provided between adjacent light emitting elements; Equipped with the first phosphor layer is a plate-like member covering the light emission surfaces of the plurality of light-emitting elements, The first phosphor layer is disposed so as to be in contact with the plurality of light-emitting elements and the filling member.

2. The light emitting device according to claim 1 , wherein, in a plan view of the light emitting surface sides of the plurality of light emitting elements, the first phosphor layer has an outer dimension substantially equal to an outer dimension of the plurality of light emitting elements.

3. The light emitting device according to claim 1 , further comprising a second phosphor layer laminated on the first phosphor layer.

4. The light emitting device according to claim 3 , wherein the second phosphor layer is made of phosphor ceramics.

5. The light emitting device according to claim 3 , wherein, in a plan view of the light emitting surface sides of the plurality of light emitting elements, an outer dimension of the second phosphor layer is substantially equal to an outer dimension of the first phosphor layer.

6. 4. The light emitting device of claim 3, wherein the second phosphor layer is adhered to the first phosphor layer.

7. The light emitting device according to claim 3 , wherein a side surface of the first phosphor layer and a side surface of the second phosphor layer are covered with the filling member.

8. The light emitting device according to claim 1 , wherein the filling member includes a reflective material that reflects light.

9. The light emitting device of claim 3 , further comprising one or more phosphor layers disposed on the second phosphor layer.

10. Further comprising a third phosphor layer laminated on the second phosphor layer; The light emitting device according to claim 3 , wherein the third phosphor layer includes phosphor particles and a resin in which the phosphor particles are dispersed.

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