Light emitting device

Abstract

This light emitting device (1) is provided with: a plurality of light emitting elements (10) which are disposed at specific intervals; a first phosphor layer (20) which is composed of a phosphor ceramic; and filling members (30, 30A) which cover the side surfaces of the plurality of light emitting elements (10) and are provided between light emitting elements (10) that are adjacent to each other. The first phosphor layer (20) is a single plate-shaped member that covers light exit surfaces of the plurality of light emitting elements (10), and the first phosphor layer (20) is disposed so as to be in contact with the plurality of light emitting elements (10) and the filling members (30, 30A).

Description

Light-emitting device

[0001] The present disclosure relates to a light emitting device.

[0002] In recent years, light-emitting devices that combine a light-emitting element such as a light-emitting diode (LED) or a laser diode (LD) with a phosphor have become widespread. Such light-emitting devices are used as light sources for image display devices such as displays and projectors, as well as for 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 connected to a circuit board, a housing surrounding the light emitting diode, and a light emitting device component including an encapsulating resin layer capable of encapsulating the light emitting diode and a phosphor layer formed on the surface of the encapsulating resin layer.

[0004] JP 2012-28666 A

[0005] In a light-emitting device that combines a light-emitting element and a phosphor, the temperature of the phosphor layer may increase due to heat emitted from the phosphor, resulting in a decrease in light-emitting intensity over time (thermal quenching). Therefore, in order to suppress thermal quenching, it is necessary to dissipate heat from the phosphor layer. However, in Patent Document 1, a sealing resin layer with low thermal conductivity is present between the phosphor layer and the light-emitting diode, which results in insufficient heat dissipation from the phosphor layer, making it difficult to suppress thermal quenching of the phosphor.

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

[0007] In order to solve the above problems, a light emitting device according to an aspect of the present disclosure includes a plurality of light emitting elements arranged at a predetermined interval, a first phosphor layer made of phosphor ceramic, 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 emitting 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.

[0008] FIG. 1A is a cross-sectional view showing an example of a light-emitting device according to a first embodiment. FIG. 1B is a plan view showing the light-emitting device according to FIG. 1A in a planar view. FIG. 1C is a plan view showing the light-emitting device of FIG. 1B in a state where the first phosphor layer is removed. FIG. 2A is a cross-sectional view illustrating a heat dissipation path in the light-emitting device according to the first embodiment. FIG. 2B is a plan view illustrating a heat dissipation path in the light-emitting device according to the first embodiment. FIG. 3A is a cross-sectional view showing an example of a light-emitting device according to a second embodiment. FIG. 3B is a plan view showing the light-emitting device according to FIG. 3A in a planar view. FIG. 4 is a cross-sectional view showing another example of a light-emitting device according to the second embodiment. FIG. 5 is a cross-sectional view showing an example of a light-emitting device according to a third embodiment. FIG. 6 is a diagram showing the results of a beam profile in the light-emitting device of Example 1-1. FIG. 7 is a diagram showing the results of a beam profile in the light-emitting device of Example 1-2. FIG. 8 is a front view showing the overall shape of an analytical model used in the CAE analysis of Example 2. FIG. 9 is a perspective view showing a light-emitting module in the analytical model used in the CAE analysis. FIG. 10A is a plan view showing a light-emitting module in the analytical model used in the CAE analysis. FIG. 10B is a front view showing a light-emitting module in the analytical model used in the CAE analysis. FIG. 11 is a schematic diagram showing a light-emitting device in the analytical model used in the CAE analysis. FIG. 12 is a plan view illustrating the arrangement of the light-emitting element and dam material in the light-emitting device in the analytical model used in the CAE analysis. FIG. 13 is a plan view illustrating the arrangement of the phosphor layer, filler material, and dam material in the light-emitting device in the analytical model used in the CAE analysis. FIG. 14 is a table showing the structures and CAE analysis results of the light-emitting devices of Examples 2-1 to 2-3 and Comparative Examples 2-1 to 2-3. FIG. 15 is a contour diagram showing the temperature distribution on the surface of the light-emitting surface side of the first phosphor layer in the CAE analysis of the light-emitting devices of Example 2-1, Comparative Example 2-1, and Comparative Example 2-3. Fig. 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. 15. Fig. 17 is a contour diagram showing the temperature distribution on the surface of the light-emitting surface side of the first phosphor layer and the temperature distribution on the surface of the light-emitting surface side of the second phosphor layer in CAE analysis of the light-emitting devices of Example 2-2, Example 2-3, and Comparative Example 2-2.Fig. 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. Fig. 19 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.

[0009] The light emitting device according to this embodiment will be described in detail below with reference to the drawings. Note that the dimensional proportions in the drawings are exaggerated for the sake of explanation and may differ from the actual proportions.

[0010] [First embodiment] As shown in Figures 1A and 1B, the light-emitting device 1 according to this embodiment includes a plurality of light-emitting elements 10, a first phosphor layer 20 made of phosphor ceramic, and a filler member 30 covering the side surfaces of the plurality of light-emitting elements 10.

[0011] 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.

[0012] A white substrate with high light reflectivity may be used as the substrate 40. 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 may be used as such a substrate 40. The shape of the substrate 40 when viewed from above is not particularly limited, and may be rectangular as shown in FIG. 1B, circular, or polygonal.

[0013] The plurality of 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 will be described later, a filler member 30 is filled between adjacent light-emitting elements 10.

[0014] The light-emitting element 10 has an upper surface 11 which is a light-emitting surface from which excitation light is emitted. The plurality of 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 bonding wires for power supply. Note that although the number of light-emitting elements 10 is four in FIG. 1C , there is no particular limitation as long as it is plural.

[0015] 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, or can 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 properties 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, but 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.

[0016] The first phosphor layer 20 is made of phosphor ceramics obtained by sintering a phosphor. Because 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.

[0017] Here, for example, (Ga, Sc) ２ O ３ : Cr ３＋The thermal conductivity of phosphor ceramics made by sintering phosphors is about 8.6 W / m·K. ３ Ga ２ (GaO ４ ) ３ : Cr ３＋ The thermal conductivity of phosphor ceramics obtained by sintering a phosphor is about 6.5 W / m·K. ３ Al ５ O １２ : Ce ３＋ The thermal conductivity of phosphor ceramics, which are made by sintering a phosphor, is about 10 W / m·K. In contrast, the thermal conductivity of a wavelength conversion member 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 wavelength conversion member, and therefore the heat generated by the phosphor can be dissipated efficiently.

[0018] 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 with 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.

[0019] The blue phosphor has an emission peak in the wavelength range of 470 nm to 500 nm, the green phosphor has an emission peak in the wavelength range of 500 nm to 540 nm, and the yellow phosphor has an emission peak in the wavelength range of 545 nm to 595 nm. １０ O １７ :Eu ２＋ , CaMgSi ２ O ６ :Eu ２＋ , Ba ３ MgSi ２ O ８ :Eu ２＋ , Sr １０ (P.O. ４ ) ６ Cl ２ :Eu ２＋ Examples of green phosphors include (Ba, Sr) ２ SiO ４ :Eu ２＋ , Ca８ Mg(SiO ４ ) ４ Cl ２ :Eu ２＋ , Ca ８ Mg(SiO ４ ) ４ Cl ２ :Eu ２＋ , Mn ２＋ Examples of yellow phosphors include (Sr, Ba) ２ SiO ４ :Eu ２＋ , (Y, Gd) ３ Al ５ O １２ : Ce ３＋ , Ca-α-SiAlON:Eu ２＋ Examples include:

[0020] The red phosphor is excited by the light emitted from the light emitting element 10 or at least one of the green phosphor and yellow phosphor, and emits red light. The red phosphor has an emission peak in the wavelength range of 600 nm to 650 nm. For example, Sr ２ Si ５ N ８ :Eu ２＋ , CaAlSiN ３ :Eu ２＋ (CASN), SrAlSi ４ N ７ :Eu ２＋ , CaS:Eu ２＋ , La ２ O ２ S: EU ３＋ , Y ３ Mg ２ (AlO ４ ) (SiO ４ ) ２ : Ce ３＋ Examples include:

[0021] 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:

[0022] In near-infrared phosphors, the preferred fluorescent ion is Cr ３＋ Cr as a fluorescent ion 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, depending on the type of host, it is easy to change the light absorption peak wavelength and / or the fluorescence peak wavelength, which is advantageous in changing the excitation spectrum shape and the fluorescence spectrum shape.

[0023] The near-infrared phosphor is Cr ３＋ Specifically, the near-infrared phosphor is a phosphor comprising a metal composite oxide activated with Cr, which is a base material made of at least one selected from the group consisting of borates, phosphates, silicates, aluminates, gallates, germanates, tungstates, and metal oxides. ３＋ Such a near-infrared phosphor is preferably a phosphor activated with CeSc. ３ (BO ３ ) ４ : Cr ３＋ , (La, Y, Sc) ４ (BO ３ ) ４ : Cr ３＋ , LaSc ３ (BO ３ ) ４ : Cr ３＋ , ScBO ３ : Cr３＋ ,KiI.P ２ O ７ :Cr ３＋ ,Sr ３ I am ３ O １２ :Cr ３＋ ,Sr ９ In (P) ４ ) ７ :Cr ３＋ 、Nitrogen ２ O ６ :Cr ３＋ ,Mg ２ Al ４ Yes ５ O １８ :Cr ３＋ 、No ３ (Ga,Gd) ５ Yes １４ :Cr ３＋ 、No ３ (Ga, Al) ５ SiO １４ :Cr ３＋ 、LaMgGaa １１ O １９ :Cr ３＋ ,Mg ３ Go ２ Yes ８ :Cr ３＋ 、Li(In,Sc)Ge ２ O ６ :Cr ３＋ ,Zn ３ (Ga,Al)Ge ２ O １０ :Cr ３＋ , Li Mẽ ２ I am ２ O ８ :Cr ３＋ 、Nana ２ Go ５ O １４ :Cr ３＋ 、NaGTA'WO ６ :Cr ３＋ , (Ga, Sc) ２ O ３ :Cr ３＋ 、LaLuO ３ :Cr ３＋ 、Ba ３ Sc ４ O ９ :Cr ３＋ ,Zn２ SnO ４ : Cr ３＋ , LiIn ２ SbO ６ : Cr ３＋ , LiSrAlF ６ : Cr ３＋ It can be at least one selected from the group consisting of:

[0024] 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 with RE is, for example, ３ B' ２ (AlO ４ ) ３ : Cr ３＋ , R.E. ３ B' ２ (GaO ４ ) ３ : Cr ３＋ It is represented by the general formula: where RE is a rare earth element, and B' is at least one element selected from Al, Ga, and Sc.

[0025] The near-infrared phosphor is preferably at least one of a rare earth aluminum garnet phosphor and a rare earth gallium garnet phosphor. ３ Al ２ (AlO ４ ) ３ : Cr ３＋ , La ３ Al ２ (AlO ４ ) ３ : Cr ３＋ , Gd ３ Al ２ (AlO ４ ) ３ : Cr ３＋ , Y ３ Ga ２ (AlO ４ ) ３ : Cr ３＋ , La ３ Ga ２ (AlO ４ ) ３ : Cr ３＋ , Gd３ Ga ２ (AlO ４ ) ３ : Cr ３＋ , Y ３ Sc ２ (AlO ４ ) ３ : Cr ３＋ , La ３ Sc ２ (AlO ４ ) ３ : Cr ３＋ , Gd ３ Sc ２ (AlO ４ ) ３ : Cr ３＋ , Y ３ Ga ２ (GaO ４ ) ３ : Cr ３＋ , La ３ Ga ２ (GaO ４ ) ３ : Cr ３＋ , Gd ３ Ga ２ (GaO ４ ) ３ : Cr ３＋ , Y ３ Sc ２ (GaO ４ ) ３ : Cr ３＋ , La ３ Sc ２ (GaO ４ ) ３ : Cr ３＋ , Gd ３ Sc ２ (GaO ４ ) ３ : Cr ３＋ It is preferable that the polymerizable compound is at least one selected from the group consisting of:

[0026] 1A and 1C , the filling member 30 is formed on the main surface 41 of the substrate 40 so as to cover the peripheries of the plurality of light-emitting elements 10. Specifically, when viewed in plan, the filling member 30 is arranged 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. Furthermore, the filling member 30 is provided so as to fill the gaps between adjacent light-emitting elements 10.

[0027] The material of the filler 30 is not particularly limited as long as it is made of a thermally conductive material. Preferably, the filler 30 includes a reflective material that reflects light. When the filler 30 includes a reflective material, the reflective material reflects the excitation light emitted from the light-emitting element 10 and the fluorescence emitted from the phosphor, thereby improving the luminous efficiency of the light-emitting device 1.

[0028] The filler member 30 may be, for example, a curable white silicone resin. The curable white silicone resin is a resin obtained by dispersing a white pigment in a silicone resin. The white pigment may be 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. The curable white silicone resin may also contain an inorganic filler to enhance the strength and thermal conductivity of the cured product. The inorganic filler may be 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.

[0029] As shown in FIGS. 1A to 1C, a dam material 50, which serves as a side wall, is provided on the outer periphery of the filler member 30 provided around the plurality of light-emitting elements 10. The dam material 50 stands upright 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 filler member 30. By providing the dam material 50 on the entire outer periphery of the filler member 30, the filler 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 filler member 30 and the stack of the light-emitting elements 10 and the first phosphor layer 20.

[0030] The material constituting the dam material 50 is not particularly limited, and may be at least one selected from the group consisting of metal, resin, and ceramic. Furthermore, since the dam material 50 preferably has light reflectivity, it is more preferable that the dam material 50 be made of a light reflecting material.

[0031] In the light-emitting device 1, the first phosphor layer 20 is laminated on the upper surfaces 11 of the plurality of light-emitting elements 10 and is a single plate-like member covering the light-emitting 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-emitting surfaces of the four light-emitting elements 10 but also the upper surfaces of the filler members 30A located between adjacent light-emitting elements 10. The first phosphor layer 20 may be laminated directly on the upper surfaces 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 for example, at least one of an inorganic adhesive and an organic adhesive having optical transparency may be used.

[0032] The first phosphor layer 20 is in contact with the upper surfaces 11 of the plurality of light-emitting elements 10 and the upper surface 31A of the filler 30A located between 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 plurality of light-emitting elements 10 and the upper surface 31A of the filler 30A. Furthermore, when the first phosphor layer 20 is adhered to the plurality of light-emitting elements 10 by an adhesive layer, the first phosphor layer 20 may be in contact with the upper surfaces 11 of the plurality of light-emitting elements 10 and the upper surface 31A of the filler 30A located between adjacent light-emitting elements 10 via the adhesive layer. In this way, by having the first phosphor layer 20 in contact with the upper surfaces 11 of the plurality of 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 and dissipated, as described below.

[0033] 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 preferably approximately equal to the outer dimensions of the plurality of light-emitting elements 10. Specifically, as shown in FIGS. 1B and 1C, the outer dimension W1 of the first phosphor layer 20 in the Y-axis direction is preferably approximately equal to the outer dimension W3 of the two light-emitting elements 10 including the filler member 30A. Similarly, the outer dimension W2 of the first phosphor layer 20 in the X-axis direction is preferably approximately equal to the outer dimension W4 of the two light-emitting elements 10 including the filler 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 approximately 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, making it easier for the output light to be captured by a lens provided near the light-emitting device 1. As a result, it is possible to miniaturize 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 inside can also be made smaller.

[0034] In this specification, the phrase "the outer dimensions of the first phosphor layer 20 are substantially the same as 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.

[0035] 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 portion of the excitation light is absorbed by fluorescent ions of the phosphor contained in the first phosphor layer 20. The excitation light is then converted into fluorescence by electron energy transition of the fluorescent ions, and the fluorescence is emitted upward from the phosphor.

[0036] Here, when absorbing excitation light and converting the wavelength of the light into fluorescence, the phosphors in the first phosphor layer 20 generate heat. However, the phosphors that generate heat primarily are those in the region that is primarily irradiated with excitation light. That is, the phosphors that generate heat primarily are those in the region 22 surrounded by the dashed-dotted line in FIGS. 2A and 2B, specifically, the phosphors located directly above the light-emitting element 10. In contrast, phosphors in the first phosphor layer 20 that are not located directly above the light-emitting element 10, i.e., those in the region 23 not surrounded by the dashed-dotted line in FIGS. 2A and 2B, generate little or very little heat because they are irradiated with a small amount of excitation light. Therefore, as shown by the arrows in FIGS. 2A and 2B, heat conduction occurs from the region 22 that generates a large amount of heat toward the region 23 that generates a small amount of heat.

[0037] Filler 30A is located below region 23, which generates less heat, and upper surface 31A of filler 30A abuts 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.

[0038] Furthermore, as described above, the first phosphor layer 20 is in contact with the upper surfaces 11 of the plurality of 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.

[0039] As described above, in the light-emitting device 1 of the present embodiment, heat generated in the region 22 of the first phosphor layer 20 is conducted to the relatively low-temperature region 23, and then conducted from the region 23 to the filler member 30A, and then conducted to the substrate 40. At the same time, heat generated in the region 22 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 22 of the first phosphor layer 20, and it is possible to suppress temperature quenching of the phosphor contained in the region 22.

[0040] If the filler member 30A located between adjacent light-emitting elements 10 were not provided, an air layer would exist between the adjacent light-emitting elements 10. However, because the air layer has low thermal conductivity, it would be difficult to dissipate the heat conducted to region 23. However, in the light-emitting device 1, the filler member 30A is provided, so it is possible to conduct the heat from region 23 to the substrate 40 via the filler member 30A.

[0041] Furthermore, 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 will spread and irradiate the entire first phosphor layer 20. As a result, heat will be generated throughout the entire first phosphor layer 20, making it difficult to create a relatively low-temperature region 23, which may result in insufficient heat dissipation from the first phosphor layer 20. Therefore, in order to create the relatively low-temperature region 23, the first phosphor layer 20 needs to be in contact with a plurality of light-emitting elements 10.

[0042] In the light-emitting device 1 shown in FIG. 1A , the height of the filler 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 surfaces of the first phosphor layer 20 are not in contact with the filler member 30. However, this embodiment is not limited to this configuration. For example, the height of the filler 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 surfaces of the first phosphor layer 20 may be in contact with the filler member 30. In this way, since the side surfaces of the first phosphor layer 20 are covered with the filler member 30, heat generated in the first phosphor layer 20 can be conducted to the filler member 30 and dissipated. Therefore, the heat dissipation properties of the first phosphor layer 20 can be further improved.

[0043] Furthermore, when the light emitting device 1 is viewed from the light emitting surface side of the plurality of light emitting elements 10 in a plan view, the outer dimensions of the first phosphor layer 20 are substantially the same as 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, allowing the lens to be made smaller.

[0044] 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 redundant description will be omitted.

[0045] 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.

[0046] 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, with adjacent light-emitting elements 10 spaced apart from each other at a predetermined interval.

[0047] The first phosphor layer 20 is made of phosphor ceramics obtained by sintering a phosphor, and is a plate-like member that covers the light-emitting surfaces of the plurality of light-emitting elements 10. The filler member 30 is arranged 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 filler member 30 is also arranged so as to fill the gaps between adjacent light-emitting elements 10. A dam material 50, which serves as a sidewall, is provided on the outer periphery of the filler member 30 arranged around the plurality of light-emitting elements 10.

[0048] The first phosphor layer 20 covers not only the light-emitting surfaces of the four light-emitting elements 10 but also the upper surfaces of the filler members 30A located between adjacent light-emitting elements 10. The first phosphor layer 20 may be laminated directly onto the upper surfaces 11 of the plurality of light-emitting elements 10, or may be laminated via an adhesive layer.

[0049] 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 properties of the first phosphor layer 20 are 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, it is possible to obtain a light emitting device that can emit fluorescence of multiple wavelengths.

[0050] The second phosphor layer 60 may be made of phosphor ceramics obtained by sintering a phosphor, or may be a wavelength conversion material in which phosphor particles are dispersed in a translucent material such as silicone resin. However, the second phosphor layer 60 is preferably made of phosphor ceramics obtained by sintering a phosphor. This allows for efficient dissipation of heat emitted from the phosphor in the second phosphor layer 60 and suppresses temperature quenching of the phosphor.

[0051] 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 those described above.

[0052] 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 that covers 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 for example, at least one of an inorganic adhesive and an organic adhesive that is optically transparent can be used.

[0053] In the light-emitting device 2, when the light-emitting surface side of the plurality of light-emitting elements 10 is viewed in plan, the outer dimensions of the second phosphor layer 60 are preferably approximately equal to the outer dimensions of the first phosphor layer 20. Specifically, as shown in FIG. 3B , 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 preferably approximately equal. Similarly, 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 preferably approximately equal. By making the outer dimensions of the first phosphor layer 20 and the second phosphor layer 60 approximately 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, making it easier for the output light to be captured by a lens provided near the light-emitting device 2. As a result, it is possible to reduce the size of the lens provided near 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.

[0054] In this specification, the phrase "the outer dimensions of the second phosphor layer 60 are substantially the same as the outer dimensions 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.

[0055] 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 portion of the excitation light is absorbed by fluorescent ions of the phosphor contained in the first phosphor layer 20. Similarly, a portion of the excitation light is absorbed by fluorescent ions of the phosphor contained in the second phosphor layer 60. The excitation light is then converted into fluorescence by electron energy transition of the fluorescent ions, and the fluorescence is emitted upward from the phosphor. Note that the light-emitting device 2 may be configured so 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.

[0056] Here, when absorbing excitation light and converting the wavelength of the light into fluorescence, the phosphors in the first phosphor layer 20 and the second phosphor layer 60 generate heat. However, the phosphors that generate heat primarily are those in the region that is primarily irradiated with excitation light. That is, the phosphors that generate heat primarily are those in the region 22A surrounded by the dashed-dotted line in FIGS. 3A and 3B, specifically, those located directly above the light-emitting element 10. In contrast, the phosphors in the first phosphor layer 20 and the second phosphor layer 60 that are not located directly above the light-emitting element 10, i.e., those in the region 23A not surrounded by the dashed-dotted line in FIGS. 3A and 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 FIGS. 3A and 3B, heat conduction occurs from the region 22A where the amount of heat generation is large to the region 23A where the amount of heat generation is small.

[0057] Filler 30A is located below region 23A, which generates less heat, and upper surface 31A of filler 30A abuts region 23A. Therefore, heat conducted to region 23A is conducted from region 23A to filler 30A, and heat conducted to filler 30A is conducted from filler 30A to substrate 40.

[0058] Furthermore, as described above, the first phosphor layer 20 abuts against the upper surfaces 11 of the plurality of 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.

[0059] 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, making it possible to suppress temperature quenching of the phosphors contained in the region 22A.

[0060] 3A, the height of the filler member 30 that covers 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 surfaces of the first phosphor layer 20 and the second phosphor layer 60 are not in contact with the filler member 30. However, this embodiment is not limited to this configuration.

[0061] 4 , the height of the filler 30 may be approximately the same as the height of the stack 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 filler 30. In this way, by covering the side surfaces of the first phosphor layer 20 and the second phosphor layer 60 with the filler 30, heat generated in the first phosphor layer 20 and the second phosphor layer 60 can be conducted to the filler 30 and dissipated. This makes it possible to further improve the heat dissipation properties of the first phosphor layer 20 and the second phosphor layer 60.

[0062] 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 redundant description will be omitted.

[0063] 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 predetermined intervals, a first phosphor layer 20, and filler members 30 and 30A. Similar 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 filler member 30.

[0064] 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 stacked 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 that can emit fluorescence of multiple wavelengths.

[0065] 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 translucent material. The translucent material used in the wavelength conversion member may be a resin, such as a silicone resin. The phosphor contained in the third phosphor layer 70 is not particularly limited, but may be at least one of a blue phosphor, a green phosphor, a yellow phosphor, a red phosphor, and a near-infrared phosphor. The blue phosphor, the green phosphor, the yellow phosphor, the red phosphor, and the near-infrared phosphor may be any of those described above.

[0066] 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 that covers 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 together is not particularly limited, and for example, at least one of an inorganic adhesive and an organic adhesive having optical transparency may be used.

[0067] 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, excitation light (primary light) is emitted upward from the light-emitting element 10. 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 portion of the excitation light is absorbed by fluorescent ions of the phosphors contained in the first phosphor layer 20 and the second phosphor layer 60. Similarly, a portion of the excitation light is absorbed by fluorescent ions of the phosphors contained in the third phosphor layer 70. The fluorescent ions are then converted into fluorescence by 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 fluorescence emitted from the phosphors in the first phosphor layer 20 and / or the second phosphor layer 60 is absorbed by the phosphors in the third phosphor layer 70, thereby emitting fluorescence of a longer wavelength.

[0068] In the light emitting device 4, the phosphor contained in the first phosphor layer 20 is a near-infrared phosphor (Ga, Sc) ２ O ３ : Cr ３＋ The phosphor contained in the second phosphor layer 60 is a near-infrared phosphor, Gd ３ Ga ２ (GaO ４ ) ３ : Cr ３＋ The phosphor contained in the third phosphor layer 70 is a red phosphor, CaAlSiN ３ :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.

[0069] In the light-emitting device 4, the third phosphor layer 70 is preferably a wavelength conversion material 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. This allows for improved light extraction efficiency from the light-emitting device 4.

[0070] (Additional Notes) The above description of the embodiments discloses the following techniques.

[0071] (Technology 1) A light emitting device comprising: a plurality of light emitting elements arranged at predetermined intervals; a first phosphor layer made of phosphor ceramic; and a filler member covering the side surfaces of the plurality of light emitting elements and provided between adjacent light emitting elements; wherein the first phosphor layer is a plate-like member covering the light emitting 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.

[0072] With this configuration, heat generated in region 22 of first phosphor layer 20 is conducted to relatively low-temperature region 23, and then from region 23 to filler member 30A, and then 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 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.

[0073] (Technology 2) A light-emitting device according to Technology 1, wherein, when viewed in plan from the light-emitting surface side of the plurality of light-emitting elements, the outer dimensions of the first phosphor layer are approximately equal to the outer dimensions of the plurality of light-emitting elements.

[0074] This configuration makes it difficult for the output light emitted from the light-emitting device to diffuse. This makes it easier for the output light to be captured by a lens installed near the light-emitting device, allowing the lens to be made smaller. Furthermore, by making the lens smaller, the housing that holds the lens and the light-emitting device inside can also be made smaller.

[0075] (Technology 3) The light emitting device according to Technology 1 or 2, further comprising a second phosphor layer laminated on the first phosphor layer.

[0076] In the light emitting device of this embodiment, the heat dissipation properties of the first phosphor layer 20 are improved, and therefore, even if the second phosphor layer 60 is further laminated on the first phosphor layer 20, it is possible to suppress a temperature rise in the first phosphor layer 20. Furthermore, by providing the second phosphor layer 60 in addition to the first phosphor layer 20, it is possible to obtain a light emitting device that emits fluorescence of multiple wavelengths.

[0077] (Technology 4) The light emitting device according to Technology 3, wherein the second phosphor layer is made of phosphor ceramics.

[0078] This configuration allows the heat generated from the phosphor in the second phosphor layer 60 to be efficiently dissipated, and makes it possible to suppress temperature quenching of the phosphor.

[0079] (Technology 5) A light-emitting device described in Technology 3 or 4, wherein when viewed in a plane from the light emission surface side of the plurality of light-emitting elements, the outer dimensions of the second phosphor layer are approximately equal to the outer dimensions of the first phosphor layer.

[0080] This configuration makes it difficult for the output light emitted from the light-emitting device to diffuse. This makes it easier for the output light to be captured by a lens installed near the light-emitting device, allowing the lens to be made smaller. Furthermore, by making the lens smaller, the housing that holds the lens and the light-emitting device inside can also be made smaller.

[0081] (Technology 6) The light emitting device according to any one of Technologies 3 to 5, wherein the second phosphor layer is bonded to the first phosphor layer.

[0082] This configuration allows the first phosphor layer 20 and the second phosphor layer 60 to be bonded together, thereby making it possible to tightly contact the interface between the first phosphor layer 20 and the second phosphor layer 60. This makes it easier for heat conduction to occur between the first phosphor layer 20 and the second phosphor layer 60, thereby improving the heat dissipation properties of the first phosphor layer 20 and the second phosphor layer 60.

[0083] (Technology 7) The light emitting device according to any one of Technologies 3 to 6, wherein the side surfaces of the first phosphor layer and the second phosphor layer are covered with the filling member.

[0084] With this configuration, 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.

[0085] (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.

[0086] This configuration reflects the excitation light emitted from the light-emitting element 10 and the fluorescence emitted from the phosphor, thereby suppressing the spread of light emitted from the light-emitting element 10, the first phosphor layer 20, and the second phosphor layer 60, thereby reducing light leakage, and thus improving the luminous efficiency of the light-emitting device.

[0087] (Technology 9) The light emitting device according to any one of Technologies 3 to 8, further comprising one or more phosphor layers stacked on the second phosphor layer.

[0088] 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, and therefore, even if a phosphor layer 70 is further stacked 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 that emits fluorescence of multiple wavelengths.

[0089] (Technology 10) A light emitting device described in any one of Technologies 3 to 9, further comprising a third phosphor layer laminated on the second phosphor layer, the third phosphor layer containing phosphor particles and a resin in which the phosphor particles are dispersed.

[0090] 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 ceramic and air, the light extraction efficiency from the light-emitting device can be improved.

[0091] Hereinafter, the present embodiment will be described in more detail with reference to examples and comparative examples, but the present embodiment is not limited to these examples.

[0092] [Example 1] (Preparation of First Phosphor Layer) First, a first phosphor layer to be used in a light-emitting device was synthesized using a synthesis method utilizing a solid-state reaction. The first phosphor constituting the first phosphor layer was a near-infrared phosphor (Ga ０．５９ Cr ０．０１ Sc ０．４ ) ２ O ３ In this specification, the oxide phosphor is represented by the composition formula (Ga, Sc) ２ O ３ : Cr ３＋ The phosphor is also called a "GaSc phosphor."

[0093] When synthesizing the first phosphor layer, the following compound powders were used as main raw materials: gallium oxide (Ga ２ O ３ ): Purity 4N, Asia Physical Materials Co., Ltd. Dichromium trioxide (Cr ２ O ３ ): Purity 3N, High Purity Chemical Laboratory Co., Ltd. Scandium oxide (Sc ２ O ３ ): Purity>3N, Kojundo Chemical Research Institute Co., Ltd.

[0094] In order to enhance the reactivity of the raw materials, the following compound powder was used as a reaction accelerator: boric acid (H ３ BO ３ ): Fujifilm Wako Pure Chemical Corporation

[0095] First, a compound with a stoichiometric composition (Ga ０．５９ Cr ０．０１ Sc ０．４ ) ２ O ３ The raw materials were weighed so that the desired compound (Ga ０．５９ Cr ０．０１ Sc ０．４ ) ２ O ３ 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 reaction accelerator were placed in a cylindrical container, and an appropriate amount of pure water was added. Thereafter, the container containing the raw materials, reaction accelerator, and pure water was placed in a planetary mill (PULVERISETTE5, manufactured by Fritsch Japan Co., Ltd.), and the raw materials and reaction accelerator were thoroughly wet-mixed. The rotation speed of the planetary mill was 200 rpm, and the mixing time was 30 minutes.

[0096] 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 using a dryer at 150°C for approximately 3 hours 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 approximately 512 μm. In this way, the mixed raw material for the first phosphor layer was obtained.

[0097] Next, the mixed raw material for 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 approximately 20 MPa. In this way, a molded body of the mixed raw material was obtained.

[0098] 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, thereby obtaining a sintered body of the mixed raw material.

[0099] 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 approximately 100 μm. Next, using a dicing machine (DISCO Corporation, DAD3350), the polished sintered body was diced into a thin rectangular parallelepiped shape. After dicing, the outer diameter size in a plan view was approximately 3.3 mm in length and approximately 2.6 mm in width. In this way, (Ga, Sc) ２ O ３ : Cr ３＋ The resulting mixture was sintered to obtain a first phosphor layer.

[0100] (Preparation of Second Phosphor Layer) Next, a second phosphor layer to be used in the light-emitting device was synthesized using a synthesis method utilizing a solid-state reaction. The second phosphor constituting the second phosphor layer was a near-infrared phosphor, Gd ３ (Ga ０．９７ Cr ０．０３ ) ２ Ga ３ O １２ In this specification, Gd ３ Ga ２ Ga ３ O １２ : Cr ３＋ The phosphor is also referred to as a "GGG phosphor."

[0101] When synthesizing the second phosphor layer, the following compound powders were used as the main raw materials: gadolinium oxide (Gd ２ O ３ ): Purity 4N, Japan Yttrium Co., Ltd. Gallium oxide (Ga ２ O ３ ): Purity 4N, Asia Physical Materials Co., Ltd. Dichromium trioxide (Cr ２ O ３ ): Purity 3N, Kojundo Chemical Laboratory Co., Ltd.

[0102] First, the stoichiometric compound Gd ３ (Ga ０．９７ Cr ０．０３ ) ２ Ga ３ O １２The raw materials were weighed so that the weight of the raw materials and the reaction accelerator was 0.01g. Next, the weighed raw materials and the reaction accelerator were placed in a cylindrical container, and an appropriate amount of ethanol was poured in. Thereafter, the container containing the raw materials, the reaction accelerator, and the ethanol 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.

[0103] 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.

[0104] Next, the mixed raw material for 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 approximately 20 MPa. In this way, a molded body of the mixed raw material was obtained.

[0105] The compacted mixture was then fired in a Tammann tube atmosphere electric furnace at a temperature of 1600°C for 2 hours in a nitrogen atmosphere to obtain a fired mixture.

[0106] 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, using a dicing machine (DAD3350, manufactured by Disco Corporation), the polished sintered body was diced into a thin rectangular parallelepiped shape. After dicing, the outer diameter in a plan view was about 3.3 mm in length and about 2.6 mm in width. In this way, Gd ３ Ga ２ Ga ３ O １２ : Cr ３＋The resulting second phosphor layer was sintered.

[0107] (Measurement of Density of First Phosphor Layer and 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 density of the first phosphor layer was evaluated by dividing the measured weight by the measured volume. As a result of the evaluation, the density of the first phosphor layer was found to be 4.59 g / cm ３ The density of the second phosphor layer was evaluated by Archimedes' method. As a result of the evaluation, the density of the second phosphor layer was 6.94 g / cm ３ It was.

[0108] (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, manufactured by Netsch 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, 2.67 mm ２ / s.

[0109] Since thermal conductivity is the product of density, specific heat capacity, and thermal diffusivity, the thermal conductivities of the first and second phosphor layers were calculated using this formula, and the results were 8.64 J / s / m / K and 6.52 J / s / m / K, respectively.

[0110] (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.

[0111] 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 predetermined spacing. The outer diameter of each blue LED is approximately 1.2 mm x 1.5 mm, and the spacing between adjacent blue LEDs is approximately 0.15 mm. The outer diameter of the four blue LEDs is approximately 2.6 mm x 3.2 mm.

[0112] As shown in FIG. 1C, the dam material is provided all around the four blue LEDs.

[0113] Next, a white resin filler was applied between the four blue LEDs and the dam material in the multi-chip LED package, and between adjacent blue LEDs, and then cured to form the filler. The white resin used was LED silicone KER-2016WC-A / B manufactured by Shin-Etsu Chemical Co., Ltd.

[0114] Next, the first phosphor layer was adhered onto the blue LED using an adhesive, LED silicone KER-2600-A / B manufactured by Shin-Etsu Chemical Co., Ltd.

[0115] In this way, the light-emitting device of Example 1-1 including the first phosphor layer was obtained, as shown in Figures 1A and 1B. In this example, the height of the filler member was adjusted so that the side surface of the first phosphor layer was in contact with the filler member. In addition, in the light-emitting device of Example 1-1, the difference in the outer dimensions of the four blue LEDs relative to the outer dimensions of the first phosphor layer was 5% or less.

[0116] Furthermore, a second phosphor layer was adhered onto the first phosphor layer in the light emitting device of Example 1-1, using LED silicone KER-2600-A / B manufactured by Shin-Etsu Chemical Co., Ltd. as the adhesive.

[0117] In this way, the light-emitting device of Example 1-2, which includes a first phosphor layer and a second phosphor layer, was obtained, as shown in FIG. 4 . 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. Furthermore, in the light-emitting device of Example 1-2, the difference in the outer dimensions of the four blue LEDs relative to the outer dimensions of the first phosphor layer was 5% or less. Furthermore, the difference in the outer dimensions of the first phosphor layer relative to the outer dimensions of the second phosphor layer was 5% or less.

[0118] (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, areas with high emission intensity can be considered to be areas with high heat generation.

[0119] As shown in Figure 6, in the light emitting device of Example 1-1, the area directly above the blue LEDs has a high luminous intensity and generates a lot of heat. In contrast, the area between the blue LEDs has a low luminous intensity and generates little heat. Furthermore, it is also found that the luminous intensity and heat generation are low near the side surfaces of the first phosphor layer.

[0120] 7, the light emitting device of Example 1-2 also has a high luminous intensity and generates a lot of heat in the area directly above the blue LEDs. In contrast, the area between the blue LEDs has a low luminous intensity and generates little heat. Furthermore, it is also found that the luminous intensity and heat generation are low near the side surfaces of the second phosphor layer.

[0121] 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.

[0122] (Analysis Model) Figure 8 shows the overall shape of the analysis model used in the CAE analysis, and Figures 9, 10A, and 10B schematically show the light-emitting module. As shown in Figure 8, in the CAE analysis, a spherical region made of air with a diameter of 450 mm was set 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 positioned so that the light-emitting portion (light-emitting element) was located at the center of the surrounding region 100.

[0123] 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 positioned so that the light is emitted upward (Z direction).

[0124] The aluminum base 111 is made of aluminum, and has a countersunk portion 111a on its upper surface to hold the light emitting device 1. The size of the 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 portion is 2 mm. The thermal conductivity of the aluminum base 111 is set to 138 W / m·K.

[0125] The heat sink 112 had an aluminum base 111 disposed on the upper surface thereof, and its dimensions were 59 mm length, 59 mm width, and 30 mm height. The thermal conductivity of the heat sink 112 was set to 180 W / m·K.

[0126] The fan 113 was cylindrical, and had the heat sink 112 disposed on its upper surface. The fan 113 had a diameter of 55 mm and a height of 25 mm. The fan 113 was set to generate only an upward wind at a speed of 2 m / s.

[0127] 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.

[0128] 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, filler members 30 and 30A, a substrate 40, and a dam material 50. The light emitting elements 10 are made of GaN and Si ３ N ４ The GaN had a thickness of 10 μm, a thermal conductivity of 160 W / m·K, and a calorific value of 22.07 W. ３ N ４ The thickness was set to 90 μm and the thermal conductivity was set to 85 W / m·K.

[0129] The first phosphor layer 20 was made of phosphor ceramics containing GaSc phosphor, and had 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 containing GGG phosphor, and had 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, and had a thickness of 120 μm, a thermal conductivity of 0.2 W / m·K, and a heat generation amount of 0.72 W.

[0130] A contact thermal resistance simulating an adhesive was set between the substrate 40 and the light-emitting element 10, with 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, with 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, with a thickness of 10 μm and a thermal conductivity of 0.2 W / m·K.

[0131] The filler 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 dimensions of 9 mm in length (X direction), 10 mm in width (Y direction), 0.4 mm in height (Z direction), and 1 mm in width, and had 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.

[0132] 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, with dam materials 50 provided around the entire periphery of the light-emitting elements. Adjacent light-emitting elements 10 are arranged with a predetermined spacing between them. 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. Each light-emitting element 10 has a dimension of 1.525 mm x 1.225 mm, and the spacing between adjacent light-emitting elements is 0.15 mm.

[0133] 13 shows a state in which filler members 30, 30A are provided between four light-emitting elements 10 and a dam material 50, and phosphor layers (first phosphor layer, second phosphor layer) are further laminated on the four light-emitting elements 10. The outer dimension of the phosphor layers in the Y-axis direction is 3.2 mm, and the outer dimension in the X-axis direction is 2.6 mm. In the analysis model of FIG. 13, only the phosphor layer located directly above the light-emitting elements 10 is considered to be a heat-generating region, and the phosphor layer not located directly above the light-emitting elements 10 is considered to be a non-heat-generating region.

[0134] The components and setting values ​​of the analysis model of Example 2 are summarized in Table 1, and the setting values ​​of the contact resistance between the components are summarized in Table 2. Note that the analysis conditions other than the setting values ​​in Tables 1 and 2 were as follows: ambient temperature of the surrounding area 100 was 30°C, the air speed of the fan 113 was 2.0 m / s, the air direction was the +Z direction, and gravity was the -Z direction. The CAE analysis was a steady-state analysis, and the number of cycles was 1000.

[0135]

[0136]

[0137] (Structures of Light-Emitting Devices of Examples 2-1 to 2-3 and Comparative Examples 2-1 to 2-3) The structures of the light-emitting devices of Examples 2-1 to 2-3 and Comparative Examples 2-1 to 2-3, which were subjected to CAE analysis, are shown in FIG. 14. The light-emitting device of Example 2-1 includes a light-emitting element 10, a first phosphor layer 20, filler 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, filler 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 was used as the heat-generating portion. In the light-emitting device of Example 2-3, the entire surface of the second phosphor layer 60 was used as the heat-generating portion.

[0138] The light-emitting element of Comparative Example 2-1, like Example 2-1, includes a light-emitting element 10, a first phosphor layer 20, filler 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 pieces, and further, is stacked only directly above the four light-emitting elements 10. Therefore, filler member 30A is filled between adjacent light-emitting elements 10 and adjacent first phosphor layers 20.

[0139] 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, filler 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 pieces, which are 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 pieces, which are further stacked only directly above the four light-emitting elements 10. Therefore, filler member 30A is filled between adjacent light-emitting elements 10, between adjacent first phosphor layers 20, and between adjacent second phosphor layers 60.

[0140] 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. In other words, the light emitting device of Comparative Example 2-3 has a configuration in which the filler members 30 and 30A are removed from the light emitting device of Example 2-1.

[0141] (CAE Analysis Results) FIG. 14 shows the results of the 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 example and comparative example. 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. Note that 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 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.

[0142] 16, it can be seen that the surface temperature of the first phosphor layer 20 of the light emitting device of Example 2-1 is lower overall than that of the light emitting device of Comparative Example 2-3, which 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 between diagonal distances of 2 and 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.

[0143] In this way, by forming the first phosphor layer as a single plate-like member and arranging the first phosphor layer so that it abuts against the plurality of light-emitting elements and the filler member, heat is conducted toward the region 23 that generates less heat and the filler member 30A, and as a result, it can be seen that heat is dissipated efficiently from the first phosphor layer.

[0144] 17 shows the results of CAE analysis, specifically, the temperature distribution (contour diagram) of the surfaces on the light-emitting 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.

[0145] 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.

[0146] 18, the light emitting device of Comparative Example 2-2 has a low surface temperature between diagonal distances of 2 and 2.2 mm, where the first phosphor layer is not present and the filler member is present, but the surface temperature in other areas 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 than the light emitting device of Comparative Example 2-2 between diagonal distances of 1 and 3 mm. Furthermore, the light emitting device of Example 2-3 also has a lower surface temperature than the light emitting device of Comparative Example 2-2 between diagonal distances of 1 and 3 mm.

[0147] 19, the surface temperature of the light emitting device of Comparative Example 2-2 is lower between diagonal distances of 2 and 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 surface temperature of the light emitting device of Example 2-2 is significantly lower than that of the light emitting device of Comparative Example 2-2 between diagonal distances of 1 and 3 mm. Furthermore, the surface temperature of the light emitting device of Example 2-2 is lower than that of the light emitting device of Comparative Example 2-2 between diagonal distances of 1 and 3 mm.

[0148] In this way, by forming the first phosphor layer and the second phosphor layer into a single plate-like member and arranging the first phosphor layer so that it abuts against the plurality of light-emitting elements and the filler member, heat is conducted toward the region 23A that generates less heat and the filler member 30A, which shows that heat is efficiently dissipated from the first phosphor layer and the second phosphor layer.

[0149] 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 Examples 2-1 and 2-3.

[0150] 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 compared to 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 compared to the light emitting device of Comparative Example 2-3.

[0151] Furthermore, even over 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 drop of 1.1°C lower than the light emitting device of Comparative Example 2-1, and the light emitting device of Example 2-1 had an average temperature drop of 7.2°C lower than the light emitting device 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.

[0152] In this way, by making the first phosphor layer a single plate-shaped member and arranging the first phosphor layer so that it abuts against multiple light-emitting elements and filling members, it can be seen that heat is efficiently dissipated from the entire first phosphor layer.

[0153]

[0154] Furthermore, 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 2-2 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 determined.

[0155] 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 2-2 was lower by an average of 4.5°C compared to the light emitting device of Comparative Example 2-2. Also, over the entire range of diagonal distances from 0.00 to 4.04 mm, the surface temperature of the light emitting device of Example 2-2 was lower by an average of 2.3°C compared to the light emitting device of Comparative Example 2-2. The maximum difference in the 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.

[0156] When the diagonal distance of the second 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 second phosphor layer of the light emitting device of Example 2-2 was lower by an average of 4.7°C compared to the light emitting device of Comparative Example 2-2. Also, over the entire range of diagonal distances from 0.00 to 4.04 mm, the surface temperature of the light emitting device of Example 2-2 was lower by an average of 2.8°C compared to 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.

[0157] Furthermore, 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 2-3 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 determined.

[0158] 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 2-3 was lower by an average of 3.3°C than that of the light emitting device of Comparative Example 2-2. Also, over the entire range of diagonal distances from 0.00 to 4.04 mm, the surface temperature 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 the 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.

[0159] When the diagonal distance of the second 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 second phosphor layer of the light emitting device of Example 2-3 was lower by an average of 3.5°C compared to the light emitting device of Comparative Example 2-2. Also, over the entire range of diagonal distances from 0.00 to 4.04 mm, the surface temperature of the light emitting device of Example 2-3 was lower by an average of 2.8°C compared to 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 2-3 and the light emitting device of Comparative Example 2-2 was 3.8°C.

[0160] 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 multiple light-emitting elements and a filling member, it can be seen that heat is efficiently dissipated from the entire first phosphor layer and second phosphor layer.

[0161] 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.

[0162] The entire contents of Japanese Patent Application No. 2023-185424 (filing date: October 30, 2023) are incorporated herein by reference.

[0163] According to the present disclosure, it is possible to provide a light emitting device that can efficiently dissipate heat from a phosphor layer.

[0164] 1, 2, 3, 4 Light emitting device 10 Light emitting element 20 First phosphor layer 30, 30A Filler member 60 Second phosphor layer 70 Third phosphor layer

Claims

1. A light emitting device comprising: a plurality of light emitting elements arranged at a predetermined interval; a first phosphor layer made of phosphor ceramic; and a filler member covering the side surfaces of the plurality of light emitting elements and provided between adjacent light emitting elements, wherein 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.

2. The light emitting device according to claim 1, wherein, when viewed in plan from the light emitting surface side of said plurality of light emitting elements, the outer dimensions of said first phosphor layer are approximately equal to the outer dimensions of said plurality of light emitting elements.

3. The light emitting device according to claim 1 or 2, further comprising a second phosphor layer laminated on the first phosphor layer.

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

5. A light-emitting device as described in claim 3 or 4, wherein when viewed in a planar view of the light emission surface side of the plurality of light-emitting elements, the outer dimensions of the second phosphor layer are approximately equal to the outer dimensions of the first phosphor layer.

6. The light emitting device according to 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 according to any one of claims 3 to 7, further comprising one or more phosphor layers laminated on the second phosphor layer.

10. A light emitting device as described in any one of claims 3 to 7 and 9, further comprising a third phosphor layer laminated on the second phosphor layer, the third phosphor layer containing phosphor particles and a resin in which the phosphor particles are dispersed.

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