JP2017076664A - Light-emitting device and lighting device - Google Patents

Abstract

A light-emitting device capable of suppressing a temperature rise of a phosphor layer is provided. A light emitting device (10) includes a light emitting element (2) that emits excitation light, a substrate (1) on which the light emitting element is mounted, and a plurality of phosphors that emit fluorescence by converting the wavelength of the excitation light. A phosphor layer (4) formed by bringing particles (4a) into contact with each other, wherein the phosphor layer is opposite to the surface of the light emitting element facing the substrate. It is formed on the side surface. [Selection] Figure 1

Description

  The present invention relates to a light emitting device including a phosphor layer that converts the wavelength of excitation light emitted from a light emitting element and emits fluorescence, and an illumination device including the light emitting device.

  A light-emitting device in which a light-emitting element such as an LED (Light Emitting Diode) chip is sealed with glass containing a phosphor is known as a prior art. For example, Patent Document 1 discloses an LED having a structure in which an LED chip is covered with a lens cover made of an inorganic glass containing a phosphor. Patent Document 2 discloses a light-emitting device in which phosphor particles dispersed in a low-melting glass layer are arranged on the upper surface of an LED chip. Furthermore, Patent Document 3 discloses a light emitting device in which an LED element is sealed with a glass sealing portion in which a phosphor is dispersed.

JP 2007-250817 A (published September 27, 2007) Japanese Patent Laying-Open No. 2005-72129 (published on March 17, 2005) JP 2008-124153 A (published May 29, 2008)

  However, in the case of the LED described in Patent Document 1, since the space between the LED chip and the lens cover is hollow, the heat dissipation efficiency from the lens cover to the substrate is low. For this reason, there exists a problem that a lens cover becomes high temperature.

  In the case of the light emitting device described in Patent Document 2, since the phosphor particles are dispersed in the low-melting glass, the distance between the phosphor particles is long. For this reason, there is a problem that the heat dissipation efficiency from the phosphor particles is low and the temperature of the low-melting glass rises.

  Moreover, also in the light-emitting device described in Patent Document 3, the distance between the phosphor particles dispersed in the glass sealing portion is long. Further, the distance between the phosphor particles and the LED chip and the substrate is also long. For this reason, there is a problem that the heat dissipation efficiency from the phosphor particles is low, and the temperature of the glass sealing portion is increased.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a light-emitting device capable of suppressing a temperature rise of a phosphor layer.

  In order to solve the above problems, a light-emitting device according to one embodiment of the present invention includes a light-emitting element that emits excitation light, a substrate on which the light-emitting element is mounted, a wavelength of the excitation light, and fluorescence. A phosphor layer formed by contacting a plurality of phosphor particles that emit with each other, wherein the phosphor layer includes a surface facing the substrate among surfaces of the light-emitting element. Is formed on the opposite surface.

  The light-emitting device according to one aspect of the present invention has an effect that it is possible to suppress an increase in temperature of the phosphor layer.

(A) is sectional drawing which shows the structure of the light-emitting device of Embodiment 1, (b) is sectional drawing which shows the structure of the fluorescent substance layer with which the light-emitting device shown to (a) is provided. (A) And (b) is a figure for demonstrating an example of the formation method of a fluorescent substance layer. (A)-(c) is a figure for demonstrating another example of the formation method of a fluorescent substance layer, all. It is sectional drawing which shows the structure of the light-emitting device of a comparative example. (A) is a graph which shows the relationship between input electric power and the temperature of the wavelength conversion member in the light-emitting device of Embodiment 1 and the light-emitting device of a comparative example, (b) is the light-emitting device of Embodiment 1. It is a graph which shows the relationship between input electric power and a total luminous flux ratio in the light-emitting device of a comparative example. 6 is a cross-sectional view illustrating a configuration of a light emitting device according to Embodiment 2. FIG. (A) is a graph which shows the relationship between input electric power and the temperature of the center part of the wavelength conversion member in the light-emitting device of Embodiment 2, the light-emitting device of Embodiment 1, and the light-emitting device of a comparative example, (b) ) Is a graph showing the relationship between the input power and the total luminous flux ratio in the light emitting device of the second embodiment, the light emitting device of the first embodiment, and the light emitting device of the comparative example. It is sectional drawing which shows the structure of the fluorescent substance layer with which the light-emitting device which concerns on Embodiment 3 is provided. (A) is sectional drawing which shows the structure of the light-emitting device which concerns on Embodiment 4, (b) is sectional drawing which shows another example of the structure of the light-emitting device which concerns on Embodiment 4. FIG. FIG. 6 is a cross-sectional view illustrating a configuration of a light emitting device according to Embodiment 5. It is sectional drawing which shows the structure of the illuminating device which concerns on Embodiment 6.

Embodiment 1
Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. FIG. 1A is a cross-sectional view illustrating a configuration of a light emitting device 10 according to the present embodiment. As illustrated in FIG. 1A, the light emitting device 10 includes a substrate 1, a light emitting element 2, and a phosphor layer 4. The light emitting device 10 is connected to the heat radiating member 3. Specifically, the substrate 1 included in the light emitting device 10 is connected to the heat dissipation member 3.

(Substrate 1)
The substrate 1 is a flat circular COB (Chip On Board) substrate. The shape of the board | substrate 1 is not limited to such a circular shape, Arbitrary shapes can be employ | adopted as needed. The substrate 1 is made of an inorganic material. Specifically, the substrate 1 is a ceramic substrate or a substrate in which an insulating layer is formed on an aluminum base material. Examples of the material of the ceramic substrate include alumina (thermal conductivity 20 W / (m · K)) or aluminum nitride (thermal conductivity 150 W / (m · K)).

  In the light emitting device 10 of the present embodiment, the substrate 1 is a substrate in which an insulating layer is formed on an aluminum base material. Since the thermal conductivity of aluminum is 236 W / (m · K), the thermal conductivity of the substrate 1 excluding the insulating layer is 236 W / (m · K).

  A plurality of light emitting elements 2 are mounted on the substrate 1. The substrate 1 includes an electrode (not shown), and power is supplied to the light emitting element 2 through the electrode. The board | substrate 1 is connected to the heat radiating member 3 through an attachment hole (not shown) with a screw | thread etc. FIG.

(Light emitting element 2)
The light emitting element 2 is an excitation light source that emits excitation light. The light emitting element 2 is constituted by, for example, an LED bare chip (hereinafter simply referred to as “LED chip”). In the light emitting device 10 of the present embodiment, a plurality of light emitting elements 2 are mounted on the substrate 1. The plurality of light emitting elements 2 are mounted on the substrate 1 by a face-down (flip chip) method. In the light emitting device 10 of the present embodiment, the light emitting element 2 is a flip chip type blue LED chip (peak wavelength: 440 nm to 460 nm). However, the light emitting element 2 is not limited to an LED as long as it can emit excitation light, and may be a semiconductor laser, for example. Moreover, the peak wavelength of the excitation light emitted from the light emitting element 2 is not limited to the above range, and is not limited to visible light.

  In the present embodiment, the light emitting element 2 is a flip chip having a sapphire substrate. Since the thermal conductivity of sapphire is 42 W / (m · K), the thermal conductivity of the light-emitting element 2 in the present embodiment is 42 W / (m · K). Note that a flip chip having a substrate made of a material other than sapphire may be used as the light emitting element 2.

(Phosphor layer 4)
The phosphor layer 4 is a wavelength conversion member that converts the wavelength of excitation light emitted from the light emitting element 2 to emit fluorescence. FIG. 1B is a cross-sectional view illustrating a configuration of the phosphor layer 4 included in the light emitting device 10. As shown in FIG. 1B, the phosphor layer 4 is an aggregate of a plurality of phosphor particles 4a. Further, a gap between the plurality of phosphor particles 4a is filled with a light-transmitting sealing material 4b. The gap between the plurality of phosphor particles 4a may not be filled with the sealing material 4b. The same applies to other embodiments.

  The phosphor layer 4 is formed on the surface of the light emitting element 2 opposite to the surface facing the substrate 1. The thickness of the phosphor layer 4 is not less than 100 μm and not more than 300 μm, and the chromaticity of the illumination light emitted from the light emitting device 10 is such that the chromaticity is suitable for a lighting fixture such as daylight white, warm white, or light bulb color. Is adjusted as appropriate. In this case, the distance between all the phosphor particles 4a included in the phosphor layer 4 and the light emitting element 2 is 100 μm or more and 300 μm or less. In the present embodiment, the thickness of the phosphor layer 4 is 210 μm.

The phosphor constituting the phosphor particles 4a is not particularly limited, and any phosphor can be used. In the light emitting device 10 of the present embodiment, the phosphor particles 4a are made of YAG (Y ₃ Al ₅ O ₁₂ : Ce ³⁺ , yttrium aluminum garnet) yellow phosphor. The peak wavelength of the fluorescence emitted by the YAG yellow phosphor is 540 nm to 560 nm.

  Moreover, the sealing material 4b is comprised with inorganic glass. In particular, the sealing material 4b is preferably made of silica glass from the viewpoints of transparency (low visible light absorption), thermal stability, and chemical stability.

  The thermal conductivity of silica glass is 1.4 W / (m · K) at room temperature. This value is much higher than, for example, the thermal conductivity (0.16 W / (m · K)) of the silicone resin. Therefore, by using silica glass as the sealing material 4b, heat generated in the phosphor particles 4a can be transmitted to the substrate 1 more efficiently than when a silicone resin is used as the sealing material 4b. In addition, when a resin such as a silicone resin is held at a temperature of about 150 ° C. for a long time, cracking and / or discoloration occurs. In contrast, glass such as silica glass does not crack or discolor even when held at 300 ° C. for a long time. In other words, glass is a material having higher heat resistance and higher reliability than resin.

(Heat dissipation member 3)
The heat radiating member 3 is a heat sink made of a metal material having high thermal conductivity. The heat radiating member 3 has a function of absorbing heat from the substrate 1 connected to the heat radiating member 3 and a function of releasing heat to the outside air. As shown to (a) of FIG. 1, the thermal radiation member 3 has a high thermal radiation effect by providing a saw blade-shaped thermal radiation fin in the surface facing the surface where the board | substrate 1 is connected.

  The constituent material of the heat radiating member 3 in this embodiment is aluminum. However, the material of the heat radiating member 3 is not limited to aluminum, and other materials may be used. The thermal conductivity of aluminum is 236 W / (m · K). For this reason, the thermal conductivity of the heat radiating member 3 in this embodiment is about 236 W / (m · K).

(Method for forming phosphor layer 4)
An example of a method for forming the phosphor layer 4 will be described with reference to FIG. FIGS. 2A and 2B are diagrams for explaining an example of a method for forming the phosphor layer 4.

  As an example of a method of forming the phosphor layer 4 on the light emitting element 2, a method of forming the phosphor layer 4 on the LED wafer can be given. In this case, first, an aggregate of film-like phosphor particles 4a is formed on the LED wafer 2W (see FIG. 2A) in a silicon alkoxide solution. Here, by forming the aggregate of the phosphor particles 4a in the silicon alkoxide solution as described above, the silica precursor generated by hydrolysis of the silicon alkoxide emits light with the phosphor particles 4a or with the phosphor particles 4a. When the element 2 comes into contact, it acts as a binder, and an effect that the mechanical strength of the phosphor layer 4 is improved is obtained.

  Next, the LED wafer is taken out from the silicon alkoxide solution, and a sol-gel solution containing a silica glass precursor is filled in the gaps present in the phosphor particles 4a. Thereafter, the phosphor particles 4a in which the gap is filled with the sol-gel solution are heat-treated, thereby obtaining the LED wafer 2W having the phosphor layer 4 formed on the surface as shown in FIG. Furthermore, by dividing the LED wafer 2W, the light emitting element 2 (LED chip) on which the phosphor layer 4 is formed as shown in FIG. 2B is obtained.

  In this case, when the light emitting device 10 is manufactured, it is only necessary to mount the light emitting element 2 on which the phosphor layer 4 is formed in advance on the substrate 1. That is, when the light emitting device 10 is manufactured, a molding process for molding the phosphor layer 4 on the light emitting element 2 is not required, and thus the manufacturing process of the light emitting device 10 is rationalized.

  Another example of the method for forming the phosphor layer 4 on the light emitting element 2 will be described with reference to FIG. FIGS. 3A to 3C are views for explaining another example of the method for forming the phosphor layer 4.

  As another example of the method for forming the phosphor layer 4 on the light emitting element 2, there is a method for forming the phosphor layer 4 on the light emitting element 2 mounted on the substrate 1. In this case, first, the light emitting element 2 is mounted on the substrate 1.

  Next, the masking jig 8 is disposed on the substrate 1. FIG. 3A is a top view showing the shape of the masking jig 8. As shown in FIG. 3A, the masking jig 8 is a plate-like jig having a shape corresponding to the shape of the substrate 1. Further, the masking jig 8 is provided with a hole in a portion corresponding to the light emitting element 2 on the substrate 1. Therefore, the masking jig 8 disposed on the substrate 1 covers a portion other than the light emitting element 2 on the substrate 1.

  With the masking jig 8 disposed on the substrate 1, the phosphor layer 4 is formed on the masking jig 8 and the light emitting element 2 as shown in FIG. Here, the method for forming the phosphor layer 4 is the same as the method for forming the phosphor layer 4 on the LED wafer described above. At this time, the phosphor layer 4 is not formed on the substrate 1 covered with the masking jig 8.

  Thereafter, by removing the masking jig 8 from the substrate 1, the light emitting device 10 in which the phosphor layer 4 is formed on the light emitting element 2 is obtained.

(Effect of the light emitting device 10)
As described above, the light emitting device 10 includes the phosphor layer 4. The phosphor layer 4 is formed by closely contacting a plurality of phosphor particles 4a. Further, a gap between the plurality of phosphor particles 4a is filled with a light-transmitting sealing material 4b. The phosphor particle 4a is a YAG yellow phosphor. Moreover, the sealing material 4b is silica glass.

  The phosphor particles have a thermal conductivity of about 100 times that of silicone resin and about 10 times that of glass. Specifically, the thermal conductivity of the YAG yellow phosphor is 12 W / (m · K). Moreover, the thermal conductivity of silica glass is 1.4 W / (m · K) as described above. The phosphor layer 4 is a thin film having a thickness of 300 μm or less, and is formed on the surface of the light emitting element 2 opposite to the surface facing the substrate 1. For this reason, the heat dissipation path from the phosphor layer 4 to the substrate 1 is short. Moreover, the thickness of the fluorescent substance layer 4 is 100 micrometers or more. For this reason, the ratio of the light emitted without wavelength conversion among the excitation light incident on the phosphor layer 4 is adjusted. Thereby, the chromaticity of the illumination light which the light-emitting device 10 emits becomes chromaticity suitable as illumination light of a lighting fixture.

  In order to improve the utilization efficiency of the excitation light, the phosphor layer 4 is made as thin as possible to reduce the absorption loss of the excitation light by the light emitting element 2 or the like due to light scattering in the phosphor layer 4. It is effective. However, in the light emitting device 10, when the thickness of the phosphor layer 4 is less than 100 μm, the chromaticity of the illumination light emitted from the light emitting device 10 does not reach the chromaticity preferable as the illumination light of the lighting fixture. For this reason, the thickness of the phosphor layer 4 is set to 100 μm or more as described above.

  Therefore, most of the heat generated in the phosphor layer 4 does not pass through a medium such as air (thermal conductivity 0.035 W / (m · K)) as indicated by an arrow in FIG. Then, the heat is quickly radiated to the substrate 1 via the sealing material 4 b and the light emitting element 2. For this reason, the temperature rise of the fluorescent substance layer 4 can be suppressed. In other words, the temperature of the phosphor layer 4 can be lowered.

  Therefore, it is possible to suppress a decrease in the luminous efficiency of the phosphor particles 4a accompanying the temperature rise of the phosphor layer 4. For this reason, compared with the conventional light emitting device, the input power to the light emitting device 10 can be increased, and the total luminous flux and luminance of the light emitting device can be improved. Therefore, the light emitting device 10 is a bright light emitting device with high brightness.

(Experimental result)
An experiment was conducted on the effect of the light emitting device 10 and a comparison was made with a light emitting device 90 which is a light emitting device of a comparative example. FIG. 4 is a cross-sectional view illustrating a configuration of the light emitting device 90. As shown in FIG. 4, the light emitting device 90 includes a substrate 1, a light emitting element 2, a heat radiating member 3, a phosphor-dispersed glass plate 4 </ b> A, and a frame member 5. The phosphor-dispersed glass plate 4A is a wavelength conversion member that holds phosphor particles with glass. The frame member 5 is an annular support member that supports the phosphor-dispersed glass plate 4A. The phosphor-dispersed glass plate 4 </ b> A is separated from the light emitting element 2 by being supported by the frame member 5. Air is sealed in a closed space defined by the phosphor-dispersed glass plate 4A, the frame member 5, and the substrate 1 (in other words, a closed space in which the light emitting element 2 is disposed).

  (A) of FIG. 5 is a graph which shows the relationship between input electric power and the temperature of a wavelength conversion member in the light-emitting devices 10 and 90. FIG. FIG. 5 (a) shows (i) the temperature of the highest temperature portion of the phosphor layer 4 provided in the light emitting element 2 disposed in the center of the substrate 1, and (ii) phosphor. The relationship between the temperature of the highest temperature portion of the dispersion glass plate 4A is shown. The vicinity of the central portion of the phosphor layer 4 provided in the light emitting element 2 disposed in the center of the substrate 1 is the highest temperature portion in the light emitting device 10. In addition, the vicinity of the central portion of the phosphor-dispersed glass plate 4 </ b> A is the highest temperature portion in the light emitting device 90.

  As shown in FIG. 5A, if the input power is the same, the temperature of the highest temperature portion of the phosphor layer 4 is lower than the temperature of the highest temperature portion of the phosphor dispersed glass plate 4A. That is, in the phosphor layer 4, the temperature rise is suppressed more than the phosphor-dispersed glass plate 4A.

  FIG. 5B is a graph showing the relationship between the input power and the total luminous flux ratio in the light emitting devices 10 and 90. Here, the total luminous flux ratio is the ratio of the total luminous flux when the total luminous flux is 1 in the light emitting device 90 when the input power is 10 W.

  As shown in FIG. 5B, if the input power is the same, the total luminous flux ratio of the light emitting device 10 is larger than the total luminous flux ratio of the light emitting device 90. Further, in the light emitting device 10, the efficiency of improving the total luminous flux ratio accompanying the increase in input power is higher than that of the light emitting device 90.

[Embodiment 2]
The following will describe another embodiment of the present invention with reference to FIGS. For convenience of explanation, members having the same functions as those described in the embodiment are given the same reference numerals, and descriptions thereof are omitted.

  FIG. 6 is a cross-sectional view showing a configuration of the light emitting device 20 according to the present embodiment. As shown in FIG. 6, in the light emitting device 20, the phosphor layer 4 is also formed on the surface of the substrate 1 on which the light emitting element 2 is mounted.

  For this reason, the excitation light emitted from the side surface of the light emitting element 2 is wavelength-converted by the phosphor layer 4 on the substrate 1. For this reason, the utilization efficiency of the excitation light in the light emitting device 20 is improved as compared with the utilization efficiency of the excitation light in the light emitting device 10.

  In addition, the preferable range of the thickness of the phosphor layer 4 in the second embodiment is 100 μm or more and 200 μm or less, and the chromaticity of the illumination light of the light emitting device is neutral white, similar to the phosphor layer 4 in the first embodiment. The chromaticity is appropriately adjusted so as to have a chromaticity suitable for a lighting device such as white, warm white, or light bulb color. The thickness of the phosphor layer 4 of the present embodiment is 140 μm, which is thinner than the phosphor layer 4 of the first embodiment. This is because the use efficiency of the excitation light is improved as described above. In the light emitting device 20, since the phosphor layer 4 is thin, heat dissipation from the phosphor layer 4 is improved as compared with the light emitting device 10.

  In addition, as indicated by arrows in FIG. 6, part of the heat generated in the phosphor particles 4 a included in the phosphor layer 4 on the substrate 1 is directly transmitted to the substrate 1 without passing through the light emitting element 2. For this reason, the heat dissipation efficiency of the heat generated in the phosphor particles 4a and the total luminous flux of the light emitted from the light emitting device 20 are further improved.

  The method for forming the phosphor layer 4 on the substrate 1 and the light emitting element 2 may be the same as the method for forming the phosphor layer 4 on the LED wafer 2W described in the first embodiment. That is, after forming the phosphor layer 4 on each of the substrate 1 and the light emitting element 2, the light emitting element 2 may be mounted on the substrate 1, and the phosphor layer 4 is mounted with the light emitting element 2 mounted on the substrate 1. It may be formed. Further, the thickness of the phosphor layer 4 formed on the substrate 1 may be substantially the same as or different from the thickness of the phosphor layer 4 formed on the light emitting element 2.

  The effect of the light emitting device 20 was tested and compared with the light emitting devices 10 and 90. (A) of FIG. 7 is a graph which shows the relationship between input electric power and the temperature of a wavelength conversion member in the light-emitting devices 20, 10, and 90. FIG. In FIG. 7A, (i) the temperature of the highest temperature portion of the phosphor layer 4 of the light emitting device 20 with respect to the input power, and (ii) the center of the substrate 1 of the light emitting device 10 is arranged. The relationship between the temperature of the highest temperature portion of the phosphor layer 4 provided in the light emitting element 2 and the temperature of the highest temperature portion of the phosphor dispersed glass plate 4A is shown. . As shown in FIG. 5A, if the input power is the same, the temperature of the highest temperature portion of the phosphor layer 4 included in the light emitting device 20 is the highest temperature of the phosphor layer 4 included in the light emitting device 10. It is even lower than the temperature of the part. That is, in the phosphor layer 4 included in the light emitting device 20, the temperature rise can be further suppressed as compared with the phosphor layer 4 included in the light emitting device 10.

  FIG. 7B is a graph showing the relationship between the input power and the total luminous flux ratio in the light emitting devices 20, 10, and 90. As shown in FIG. 5B, if the input power is the same, the total luminous flux ratio of the light emitting device 20 is larger than the total luminous flux ratio of the light emitting device 10. Further, in the light emitting device 20, the efficiency of improving the total luminous flux ratio accompanying the increase in input power is higher than that in the light emitting device 10.

[Embodiment 3]
The following will describe another embodiment of the present invention with reference to FIG. The light emitting device according to this embodiment is the same as the light emitting device 20 except for the phosphor particles 4a.

FIG. 8 is a cross-sectional view illustrating a configuration of the phosphor layer 4 included in the light emitting device 30 according to the present embodiment. As shown in FIG. 8, the phosphor layer 4 included in the light emitting device 30 is not a phosphor particle 4a (see FIG. 1B), but an aggregate of a plurality of types of phosphor particles 4g and 4r. Moreover, the preferable thickness of the fluorescent substance layer 4 is 100 micrometers or more and 300 micrometers or less similarly to the case of Embodiment 1. FIG. In the present embodiment, the thickness of the phosphor layer 4 is 270 μm. The phosphor particles 4g and 4r emit fluorescence having different peak wavelengths. In the present embodiment, the phosphor particles 4g are particles of Lu ₃ Al ₅ O ₁₂ : Ce ^{3 +} green phosphor. The phosphor particles 4r are CaAlSiN ₃ : Eu ²⁺ red phosphor.

  The light emitted from the light emitting device 20 was a daylight white color temperature of 5000K and the color rendering property (Ra) was 75. On the other hand, the light emitted from the light emitting device 30 was a light bulb color with a color temperature of 3000 K, and the color rendering (Ra) was 92. That is, according to the light emitting device 30, it is possible to obtain light having a lower color temperature and higher color rendering properties than the light emitting device 20. For this reason, the light-emitting device according to the present embodiment can be suitably used for illumination such as a spotlight used in art museums, museums, clothing departments, food departments, or scenes in which light bulb color is important for color rendering.

[Embodiment 4]
The following will describe another embodiment of the present invention with reference to FIG. The light emitting device 40 in the present embodiment is the same as the configuration of the light emitting device 20 except that the light emitting device 40 includes the reflective frame member 6 or 6A.

  (A) of FIG. 9 is sectional drawing which shows the structure of the light-emitting device 40 which concerns on this embodiment. As shown to (a) of FIG. 9, the light-emitting device 20 is provided with the board | substrate 1, the light emitting element 2, the heat radiating member 3, the fluorescent substance layer 4, and the frame member 6 (reflection member) for reflection.

  The reflection frame member 6 is a frame-like member provided so as to surround the light-emitting element 2 on the surface of the substrate 1 on which the light-emitting element 2 is mounted. The reflection frame member 6 is made of a white resin. The reflecting frame member 6 reflects a part of the excitation light and fluorescence that travels in a direction deviating from the direction in which the light is emitted from the light emitting device 40 in the direction in which the light is emitted from the light emitting device 40. Thereby, the brightness | luminance of the light radiate | emitted from the light-emitting device 40 improves.

  FIG. 9B is a cross-sectional view showing another example of the configuration of the light emitting device 40 according to the present embodiment. A light emitting device 40 shown in FIG. 9B includes a reflective frame member 6 </ b> A instead of the reflective frame member 6. As shown in FIG. 9B, the reflective frame member 6A (reflective member) has an arc extending in the cross section from the substrate 1 toward the emission direction of the excitation light. The reflective frame member 6A is made of aluminum. The shape and material of the reflection frame member are not limited to the above example.

  The total luminous flux of light emitted by the light emitting device 40 was compared with the total luminous flux of light emitted by the light emitting device 20 with the same input power. In this comparison, the light emitting device 40 includes a reflective frame member 6. When the total luminous flux of the light emitted from the light emitting device 20 was 1.00, the total luminous flux of the light emitted from the light emitting device 40 was 1.05.

[Embodiment 5]
The following will describe another embodiment of the present invention with reference to FIG. In the light emitting device 50 according to the present embodiment, the phosphor layer has a plurality of layers.

  FIG. 10 is a diagram illustrating a configuration of the light emitting device 50 according to the present embodiment. As shown in FIG. 10, the light emitting device 50 includes a substrate 1, a light emitting element 2, a heat radiating member 3, a green phosphor layer 4G (first layer), and a red phosphor layer 4R (second layer).

  The green phosphor layer 4G is formed by green phosphor particles (first phosphor particles) that emit green fluorescence (fluorescence having a first peak wavelength). The red phosphor layer 4R is formed by red phosphor particles (second phosphor particles) that emit red fluorescence (fluorescence having a second peak wavelength longer than the first peak wavelength). Moreover, the preferable value of the sum of the thickness of the green phosphor layer 4G and the red phosphor layer 4R is 100 μm or more and 200 μm or less. In the present embodiment, the sum of the thicknesses of the green phosphor layer 4G and the red phosphor layer 4R is 130 μm.

In the present embodiment, the green phosphor layer 4G is formed of particles of Lu ₃ Al ₅ O ₁₂ : Ce ^{3 +} green phosphor. The peak wavelength of green fluorescence emitted by the Lu ₃ Al ₅ O ₁₂ : Ce ³⁺ green phosphor is 520 nm to 540 nm. The red phosphor layer 4R is formed of particles of CaAlSiN ₃ : Eu ²⁺ red phosphor. The peak wavelength of red fluorescence emitted by the CaAlSiN ₃ : Eu ²⁺ red phosphor is 640 nm to 660 nm.

  In the green phosphor layer 4G and the red phosphor layer 4R, silica glass is filled between the phosphor particles. Further, the green phosphor layer 4G is disposed at a position farther from the light emitting element 2 than the red phosphor layer 4R.

For this reason, the fluorescence emitted from the particles of Lu ₃ Al ₅ O ₁₂ : Ce ³⁺ green phosphor (fluorescence having the first peak wavelength) is less likely to be absorbed by the particles of CaAlSiN ₃ : Eu ²⁺ red phosphor, The use efficiency of fluorescence is improved.

  The total luminous flux of the light emitted from the light emitting device 50 was compared with the total luminous flux of the light emitted from the light emitting device according to Embodiment 3 with the same input power. When the total luminous flux of the light emitted from the light emitting device according to Embodiment 3 is 1.00, the total luminous flux of the light emitted from the light emitting device 50 is 1.05. That is, the total luminous flux of the light emitted from the light emitting device 50 was improved by about 5% compared with the total luminous flux of the light emitted from the light emitting device according to Embodiment 3 with the same input power.

[Embodiment 6]
Another embodiment of the present invention is described below with reference to FIG. In this embodiment, the lighting device 100 will be described. The lighting device 100 uses the light emitting device 10 described in the first embodiment as a light emitting device.

  FIG. 11 is a diagram illustrating a configuration of the illumination device 100 according to the present embodiment. As shown in FIG. 11, the illuminating device 100 according to the present embodiment is an illuminating device used for high ceiling lighting or the like, and is, for example, a spotlight or a downlight. As shown in FIG. 11, the illumination device 100 of the present embodiment includes a light emitting device 10, a housing 110, and a translucent plate 120, and is attached to a ceiling 130.

  The housing 110 stores the light emitting device 10 therein. The housing 110 may be formed of a light shielding member that shields illumination light output from the light emitting device 10. In the illuminating device 100 of this embodiment, the material of the housing | casing 110 is a nonflammable material and uses aluminum with high heat conductivity. Further, for example, dry air (dry air) is enclosed in the housing 110. The dew point temperature of the dry air is −35 ° C., for example, and the temperature rise of the light emitting element 2 and the phosphor layer 4 (see FIG. 1A) can be suppressed.

  The translucent plate 120 is a transparent glass plate that covers the opening of the housing 110. Note that the material of the light-transmitting plate 120 may not be inorganic glass, but it is preferable not to use a heat-sensitive resin material.

  Such an illuminating device 100 can suppress the temperature rise of the light emitting element 2 and the phosphor layer 4 in the light emitting device 10 as described in the first embodiment, and thus obtains light with higher luminance with the same input power as in the past. be able to.

  The lighting device 100 can be applied to road lighting as well as the above-described high ceiling lighting. Moreover, in the illuminating device 100 of this embodiment, all of the light-emitting device 10, the housing | casing 110, and the light transmission board 120 are comprised with inorganic materials, such as glass, a metal, or ceramics. For this reason, the illuminating device 100 can be applied suitably also to an emergency light, explosion-proof illumination, etc. Moreover, the illuminating device 100 may be provided with the light-emitting device which concerns on either of Embodiment 2-5 instead of the light-emitting device 10, for example.

[Summary]
A light emitting device (10) according to aspect 1 of the present invention includes a light emitting element (2) that emits excitation light, a substrate (1) on which the light emitting element is mounted, a wavelength of the excitation light, and fluorescence. A phosphor layer (4) formed by bringing a plurality of phosphor particles (4a) to emit light into contact with each other, wherein the phosphor layer has the above-described surface among the surfaces of the light-emitting element. It is formed on the surface opposite to the surface facing the substrate.

  According to said structure, the fluorescent substance layer which converts the wavelength of excitation light and emits fluorescence is formed when several fluorescent substance particles contact mutually. Further, the phosphor layer is formed on the surface of the light emitting element on the opposite side to the surface facing the substrate.

  Therefore, the heat radiation path from the phosphor layer to the substrate is shortened as compared with the light emitting device in which the phosphor layer and the light emitting element are separated from each other. Further, the heat generated in the phosphor particles is quickly released to the substrate on which the light emitting element is mounted via the light emitting element. For this reason, the light-emitting device which can suppress the temperature rise of a fluorescent substance layer can be provided.

  In the light emitting device according to aspect 2 of the present invention, in the aspect 1, it is preferable that the phosphor layer is also formed on a surface of the substrate on which the light emitting element is mounted.

  According to said structure, the wavelength of the excitation light radiate | emitted from the side surface of a light emitting element is wavelength-converted by the fluorescent substance layer formed on the board | substrate. In addition, since a part of the heat generated in the phosphor layer is transmitted to the substrate without passing through the light emitting element, the heat dissipation efficiency of the phosphor layer is improved. Therefore, the utilization efficiency of the excitation light emitted from the light emitting element is improved, and the temperature rise of the phosphor layer can be further suppressed.

  The light-emitting device according to aspect 3 of the present invention is the light-emitting device according to aspect 1 or 2, wherein the excitation light and the fluorescence are reflected on the surface of the substrate on which the light-emitting element is mounted (reflection frame member 6). ) Is preferably provided.

  According to said structure, the utilization efficiency of excitation light and fluorescence improves.

  The light-emitting device according to Aspect 4 of the present invention is the light-emitting device according to any one of Aspects 1 to 3, wherein the phosphor layer has a plurality of types of phosphor particles that emit fluorescence having different peak wavelengths (for example, phosphor particles 4g and 4r) may be included.

  According to said structure, it becomes possible to emit the light which has suitable color temperature and color rendering property according to the use of a light-emitting device.

  In the light-emitting device according to Aspect 5 of the present invention, in any one of Aspects 1 to 3, the phosphor layer is a first layer formed by first phosphor particles that emit fluorescence having a first peak wavelength. (Green phosphor layer 4G) and a second layer (red phosphor layer 4R) formed by second phosphor particles emitting fluorescence having a second peak wavelength longer than the first peak wavelength. The first layer may be disposed at a position farther from the light emitting element than the second layer.

  According to said structure, it becomes possible to emit the light which has suitable color temperature and color rendering property according to the use of a light-emitting device. Further, the fluorescence emitted from the first phosphor particles (that is, the fluorescence having the first peak wavelength) is the fluorescence having the peak wavelength longer than the first peak wavelength (the fluorescence having the second peak wavelength). Since it becomes difficult to be absorbed by the emitted second phosphor particles, the utilization efficiency of fluorescence is improved.

  In the light emitting device according to Aspect 6 of the present invention, in any one of Aspects 1 to 5, it is preferable that a light-transmitting sealing material (4b) is filled between the phosphor particles.

  According to said structure, the thermal radiation efficiency of a fluorescent substance layer further improves.

  In the light emitting device according to Aspect 7 of the present invention, in any one of Aspects 1 to 6, the phosphor layer preferably has a thickness of 100 μm or more and 300 μm or less.

  According to said structure, the thermal radiation efficiency of a fluorescent substance layer further improves. Moreover, the utilization efficiency of excitation light improves.

  A light-emitting device according to Aspect 8 of the present invention is the light-emitting device according to any one of Aspects 1 to 6, wherein the phosphor layer is also formed on the surface of the substrate on which the light-emitting element is mounted. The thickness is preferably 100 μm or more and 200 μm or less.

  According to said structure, the thermal radiation efficiency of a fluorescent substance layer further improves.

  An illumination device (100) according to aspect 9 of the present invention includes the light-emitting device according to any one of aspects 1 to 8.

  According to said structure, since the fall of the wavelength conversion efficiency by the heat | fever of a fluorescent substance layer can be suppressed, a high luminous flux and high-intensity illuminating device is realizable.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention. Furthermore, a new technical feature can be formed by combining the technical means disclosed in each embodiment.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Light emitting element 4 Phosphor layer 4a, 4g, 4r Phosphor particle 4b Sealing material 4G Green phosphor layer (first layer)
4R red phosphor layer (second layer)
6, 6A Reflective frame member (reflective member)
10, 20, 30, 40, 50 Light-emitting device 100 Lighting device

Claims (9)

A light emitting device that emits excitation light;
A substrate on which the light emitting element is mounted;
A phosphor layer formed by converting a wavelength of the excitation light and a plurality of phosphor particles emitting fluorescence to contact each other,
The phosphor layer is formed on a surface opposite to the surface facing the substrate among the surfaces of the light emitting element.   The light emitting device according to claim 1, wherein the phosphor layer is also formed on a surface of the substrate on which the light emitting element is mounted.   The light emitting device according to claim 1, wherein a reflection member that reflects the excitation light and the fluorescence is provided on a surface of the substrate on which the light emitting element is mounted.   The light emitting device according to any one of claims 1 to 3, wherein the phosphor layer includes a plurality of types of phosphor particles that emit fluorescence having different peak wavelengths. The phosphor layer includes a first layer formed by first phosphor particles that emit fluorescence having a first peak wavelength, and a first layer that emits fluorescence having a second peak wavelength longer than the first peak wavelength. A second layer formed by two phosphor particles,
4. The light emitting device according to claim 1, wherein the first layer is disposed at a position farther from the light emitting element than the second layer. 5.   The light emitting device according to any one of claims 1 to 5, wherein a sealing material having translucency is filled between the phosphor particles.   7. The light emitting device according to claim 1, wherein the phosphor layer has a thickness of 100 μm or more and 300 μm or less. The phosphor layer is also formed on the surface of the substrate on which the light emitting element is mounted,
7. The light emitting device according to claim 1, wherein the phosphor layer has a thickness of 100 μm or more and 200 μm or less.   An illumination device comprising the light-emitting device according to claim 1.

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