Patent Publication Number: US-2016233393-A1

Title: Light emitting device

Description:
TECHNICAL FIELD 
     The present invention relates to a light emitting device. 
     BACKGROUND ART 
     There is known a LED light emitting device in which light emitted from a LED element is wavelength-converted and then emitted to the outside.  FIG. 12  is a cross-sectional view showing a configuration of a semiconductor light emitting device  200  disclosed in Patent Literature 1. As shown in  FIG. 12 , a near-ultraviolet LED element  214  is mounted on a circuit board  211 . In addition, a blue/green light emitting portion  215  containing a blue phosphor and a green phosphor which are dispersed in a sealing material is formed on the surface of the circuit board  211  so as to directly cover the near-ultraviolet LED element  214 . Further, a red light emitting layer  222  containing a red phosphor which is dispersed in a sealing material and is a phosphor containing a hexafluorosilicate salt as a base material is disposed on the surface of the blue/green light emitting portion  215 . The blue/green light emitting portion  215  and the red light emitting layer  222  are formed to project from the circuit board  211 . 
     CITATION LIST 
     Patent Literature 
     PTL 1: Japanese Unexamined Patent Application Publication No. 2010-251621 (published on Nov. 4, 2010) 
     SUMMARY OF INVENTION 
     Technical Problem 
     In the semiconductor light emitting device  2000  shown in  FIG. 12 , the red light emitting layer  222  containing a phosphor including a hexafluorosilicate salt as the base material is formed to linearly project in a vertical direction from the circuit board  211  and have a head portion with a curved shape. In other words, the red light emitting layer  222  is not at a constant distance from a point on the surface of the circuit board  211  (hereinafter, simply referred to as a “center” of the red light emitting layer  222 ) on a center axis of the red light emitting layer  222  (a center point of the red light emitting layer  222  in a plan view) perpendicular to the circuit board  211 . 
     Therefore, the distance between the red light emitting layer  222  and the near-ultraviolet LED element  214  disposed at the center of the red light emitting layer  222  is not constant, thereby causing the problem of producing variation of a degree of change with time in emission intensity in the red light emitting layer  222  due to the light emitted from the near-ultraviolet LED element  214 . 
     The present invention has been achieved for solving the problem described above, and an object of the invention is to suppress the occurrence of variation of change with time in emission intensity in a light emitting layer containing a phosphor containing, as a base material, a fluoride represented by (Na, K) 2 (Ge, Si, Ti)F 6 :Mn. 
     Solution to Problem 
     In order to solve the problem, a light emitting device according to an embodiment of the present invention includes a substrate, a light emitting element disposed on the substrate, a sealing resin disposed on the substrate to seal the light emitting element, and a first phosphor-containing layer containing at least a red phosphor which is a phosphor containing, as a base material, a fluoride represented by (Na, K) 2 (Ge, Si, Ti)F 6 :Mn, the first phosphor-containing layer being disposed directly or indirectly on the surface of the sealing resin to cover the light emitting element and have a hemispherical shape. 
     Advantageous Effects of Invention 
     According to an embodiment of the present invention, a light emitting layer containing a phosphor containing, as a base material, a fluoride represented by (Na, K) 2 (Ge, Si, Ti)F 6 :Mn exhibits the effect of suppressing the occurrence of variation of a change with time in emission intensity in the layer. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a sectional view showing a configuration of a LED light emitting device according to embodiment 1. 
         FIG. 2  is a plan view showing a configuration of a LED light emitting device according to embodiment 1. 
         FIG. 3  is a sectional view showing a configuration of a LED light emitting device according to a comparative example. 
         FIG. 4  is a diagram showing an initial emission spectrum of a LED light emitting device according to a comparative example and an emission spectrum after emission continued for about 100 hours. 
         FIG. 5  is a diagram showing an emission spectrum of a LED light emitting device according to the present invention after emission continued for 100 hours. 
         FIG. 6  is a diagram showing a relation between the emission time and chromaticity x in xy chromaticity coordinates in each of a LED light emitting device according to embodiment 1 and a LED light emitting device according to a comparative example. 
         FIG. 7  is a diagram showing a relation between the emission time and chromaticity y in xy chromaticity coordinates in each of a LED light emitting device according to embodiment 1 and a LED light emitting device according to a comparative example. 
         FIG. 8  is a diagram showing a relation between the emission time and chromaticity x in xy chromaticity coordinates in changing the drive current of a LED light emitting device according to a comparative example. 
         FIG. 9  is a diagram showing a relation between the emission time and chromaticity y in xy chromaticity coordinates in changing in the drive current of a LED light emitting device according to a comparative example. 
         FIG. 10  is a sectional view showing a configuration of a LED light emitting device according to embodiment 2. 
         FIG. 11  is a sectional view showing a configuration of a LED light emitting device according to embodiment 3. 
         FIG. 12  is a sectional view showing a configuration of a usual semiconductor light emitting device. 
         FIG. 13  is a sectional view showing a configuration of a LED light emitting device according to a modified example of a LED light emitting device according to embodiment 3. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiment 1 
     An embodiment of the present invention is described in detail below. 
     (Configuration of LED Light Emitting Device  10 ) 
       FIG. 1  is a sectional view showing a configuration of a LED light emitting device  10  according to embodiment 1.  FIG. 2  is a plan view showing the configuration of the LED light emitting device  10  according to embodiment 1. 
     As shown in  FIGS. 1 and 2 , the LED light emitting device (light emitting device)  10  includes, on a substrate  1 , a pair of electrodes  2  and  3 , two LED elements (light emitting elements)  14   a  and  14   b , a light-transmitting resin (sealing resin)  21  which seals the LED elements  14   a  and  14   b , and a red phosphor resin (first phosphor-containing layer)  22  provided on the surface of the light-transmitting resin  21  to cover the light-transmitting layer  21 . 
     The substrate  1  serves as a wiring board on which the LED elements  14   a  and  14   b  are mounted. The substrate  1  is preferably made of a material to have a high reflecting function on a main surface as a mounting surface on which the LED elements  14   a  and  14   b  are mounted. An example of the substrate  1  is a ceramic substrate. 
     One of the electrodes  2  and  3  is an anode electrode, and the other is a cathode electrode. The electrodes  2  and  3  serve as wiring (wiring pattern) for wire bonding of the LED elements  14   a  and  14   b  formed on the substrate  1 . 
     The LED elements  14   a  and  14   b  are arranged between the electrode  2  and the electrode  3 . The LED elements  14   a  and  14   b  are connected to each other through a wire  15  made of gold or the like, and also the LED element  14   a  is connected to the electrode  2 , and the LED element  14   b  is connected to the electrode  3 . Therefore, the LED elements  14   a  and  14   b  are electrically and mechanically connected to the substrate  1 . 
     The LED elements  14   a  and  14   b  are, for example, blue LED elements which emit blue light at a peak wavelength of 450 nm. The emission color of the LED elements  14   a  and  14   b  is not limited to this, and the LED elements  14   a  and  14   b  may be ultraviolet LED elements which emit ultraviolet (near-ultraviolet) light with a peak wavelength of 390 nm to 420 nm. The emission efficiency may be improved by using the ultraviolet LED elements. 
     Also, the LED element  14   a  may be a blue LED element or ultraviolet LED element, and the LED element  14   b  may be a green LED element which emits green light. Therefore, white light may be realized by mixing the colors of blue light from the blue LED element, green light from the green LED element, and red light from the red phosphor. 
     Although the LED light emitting device  10  is described as using the two LED elements  14   a  and  14   b  in the embodiment, the number of the LED elements is not limited to 2. The LED light emitting device  10  may have only one LED element or three or more LED elements. 
     In addition, the LED light emitting device  10  using the LED elements  14   a  and  14   b  connected in series is described in the embodiment, but the LED elements  14   a  and  14   b  may be connected in parallel. 
     Further, the LED light emitting device  10  in the embodiment includes the LED elements  14   a  and  14   b  as light emitting elements, but other light emitting elements such as semiconductor lasers, organic EL elements, or the like may be used. 
     The light-transmitting resin  21  seals the LED elements  14   a  and  14   b  and the wires  15 . For example, a silicone resin can be used as the light-transmitting resin  21 . The light-transmitting resin  21  is preferably transparent but need not be necessarily transparent as long as most of the light emitted from the LED elements  14   a  and  14   b  can be transmitted. The light-transmitting resin  21  is formed on the substrate  1  so as to have a hemispherical shape. In other words, the light-transmitting resin  21  has a shape that has a constant distance (may be referred to as the “radius” of the light-transmitting resin  21  hereinafter) between the surface of the light-transmitting resin  21  (interface with the red phosphor resin  22 ) and a point (hereinafter, simply referred to as the “center” of the light-transmitting resin  21 ) on the surface of the substrate  1  and on a center axis of the light-transmitting resin  21  (a center point of the light-transmitting resin  21  in a plan view thereof) perpendicular to the substrate  1 . The light-transmitting resin  21  can be formed in a hemispherical shape on the surface of the substrate  1  by, for example, applying a transparent resin such as a silicone resin or the like on the surface of the substrate  1 . The radius of the light-transmitting resin  21  is about 0.1 mm or more and preferably about 0.4 mm or more. 
     The red phosphor resin  22  contains a red phosphor which is dispersed in a transparent resin used as a sealing material and which emits red light by the light from the LED elements  14   a  and  14   b . For example, a silicone resin can be used as the transparent resin constituting the red phosphor resin  22 . The red phosphor dispersed in the transparent resin of the red phosphor resin  22  is a phosphor containing a fluoride as a base material represented by (Na, K) 2 (Ge, Si Ti)F 6 :Mn. An example of the red phosphor is a phosphor (hereinafter referred to as “K 2 SiF 6 :Mn”) containing potassium hexafluorosilicate (K 2 SiF 6 ) as the base material. 
     The inventors of the present invention found a problem of the phosphor containing K 2 SiF 6 :Mn that the emission intensity of the phosphor decreases with the elapse of time due to light from a LED element included and light and heat generated from the LED element. 
     In particular, when a drive current allowed to flow through the LED element is a high current of 200 mA or more, the emission intensity of the phosphor containing K 2 SiF 6 :Mn significantly changes with time, and when the drive current is 300 mA, the emission intensity of the phosphor containing K 2 SiF 6 :Mn particularly significantly changes with time. 
     The problem that the emission intensity of a phosphor that is excited by primary light emitted from a LED element and emits secondary light changes with time due to the light and heat generated from the LED element is not limited to the phosphor emitting the secondary light and containing K 2 SiF 6 :Mn, and the problem can be said to generally occur in phosphors containing, as a base material, a fluoride represented by (Na, K) 2 (Ge, Si, Ti)F 6 :Mn. 
     Therefore, the red phosphor resin  22  does not directly seal the LEF elements  14   a  and  14   b  and is disposed on the surface of the light-transmitting resin  21  which seals the LED elements  14   a  and  14   b . Consequently, the red phosphor resin  22  is spaced from the LED elements  14   a  and  14   b  by a distance corresponding at least the light-transmitting resin  21  disposed thereon. Therefore, with respect to the phosphor contained in the red phosphor resin  22  and containing, as the base material, a fluoride represented by (Na, K) 2 (Ge, Si, Ti)F 6 :Mn, change with time in the emission intensity due to the light and heat emitted from the LED elements  14   a  and  14   b  can be suppressed. 
     Thus, even when the drive current allowed to flow through the LED elements  14   a  and  14   b  in order to emit light from the LED elements  14   a  and  14   b  is 200 mA or more, further about 300 mA, with respect to the phosphor containing, as the base material, a fluoride represented by (Na, K) 2 (Ge, Si, Ti)F 6 :Mn, change with time in the emission intensity due to the light and heat emitted from the LED elements  14   a  and  14   b  can be securely suppressed, and variation of the change with time in emission intensity can be suppressed in the red phosphor resin  22 . 
     In particular, the red phosphor resin  22  is spaced from the LED elements  14   a  and  14   b  by about 0.1 mm or more, preferably about 0.4 mm or more. Therefore, with respect to the phosphor contained in the red phosphor resin  22  and containing, as the base material, a fluoride represented by (Na, K) 2 (Ge, Si, Ti)F 6 :Mn, change with time in the emission intensity due to the light and heat emitted from the LED elements  14   a  and  14   b  can be more securely suppressed. 
     Further, the red phosphor resin  22  is disposed on the surface of the light-transmitting resin  21  and has a shape along the surface of the light-emitting resin  21 . 
     Specifically, the red phosphor resin  22  is formed to have a hemispherical shape together with the light-transmitting resin  21  disposed on the inner side thereof. In other words, the red phosphor resin  22  has a shape that has a constant distance (may be referred to as the “radius” of the red phosphor resin  22  hereinafter) between the surface of the red phosphor resin  22  (interface with the outside) and a point (hereinafter, may be simply referred to as the “center” of the red phosphor resin  22 ) on the surface of the substrate  1  and on the center axis of the red phosphor resin  22  (the center point of the red phosphor resin  22  in a plan view thereof) perpendicular to the substrate  1 . 
     Therefore, the light and heat emitted from the LED elements  14   a  and  14   b  are substantially uniformly transmitted to the red phosphor resin  22  as compared with a shape other than the hemispherical shape. Thus, with respect to the phosphor contained in the red phosphor resin  22  and containing, as the base material, a fluoride represented by (Na, K) 2 (Ge, Si, Ti)F 6 :Mn, variation of change with time in the emission intensity due to the light and heat emitted from the LED elements  14   a  and  14   b  can be suppressed in the red phosphor resin  22 . 
     In addition, the red phosphor resin  22  is described as being disposed directly on the surface of the light-transmitting resin  21 , but the red phosphor resin  22  may be disposed indirectly on the surface of the light-transmitting resin  21  through another layer. 
     The plurality of LED elements  14   a  and  14   b  are preferably disposed in point symmetry with respect to the center of the red phosphor resin  22 . This is because the light and heat emitted from the LED elements  14   a  and  14   b  can be transmitted as uniformly as possible to the red phosphor resin  22 . 
     The red phosphor resin  22  can be formed on the surface of the substrate  1  so as to have a hemispherical shape by, for example, applying, to the surface of the substrate  1 , a resin prepared by dispersing the phosphor containing, as the base material, a fluoride represented by (Na, K) 2 (Ge, Si, Ti)F 6 :Mn such as K 2 SiF 6 :Mn in a transparent resin such as a silicone resin (organic modified silicone, phenylsilicone resin, or the like). 
     The phosphor containing, as the base material, a fluoride represented by (Na, K) 2 (Ge, Si, Ti)F 6 :Mn has weak resistance to light and heat, and the red phosphor resin  22  has the necessity of being separated from the LED elements  14   a  and  14   b  because the red phosphor resin  22  uses a large amount of K 2 SiF 6 :Mn as an example of the red phosphor. 
     EXAMPLE 1 
     Next, Example 1 is described. An experiment was performed for comparing changes with time in emission intensity of the LED light emitting device  10  according to the embodiment and a LED light emitting device  100  according to a comparative example shown in  FIG. 3 .  FIG. 3  is a sectional view showing a configuration of the LED light emitting device  100  according to the comparative example. 
     As shown in  FIG. 3 , the LED light emitting device  100  includes, on a substrate  111 , a pair of electrodes (not shown), a LED element  114 , a red/green phosphor resin  123  which seals the LED element  114 , and a light-transmitting resin  121  provided on the surface of the red/green phosphor resin  123  so as to cover the red/green phosphor resin  123 . 
     The LED element  114  emits blue light. The LED element  114  is wire-bonded to the pair of electrodes. The red/green phosphor resin  123  is disposed on the substrate  111  to directly cover the LED element  114 . The red/green phosphor resin  123  contains a transparent resin in which a green phosphor  123 G that emits green light by the light emitted from the LED element  114  and a red phosphor  123 R that emits red light by the light emitted from the LED element  114  are dispersed. The red phosphor  123 R is K 2 SiF 6 :Mn. 
       FIG. 4  is a diagram showing an initial emission spectrum of the LED light emitting device  100  according to the comparative example and an emission spectrum after emission continued for about 100 hours (92 h). The drive current allowed to flow through the LED element  114  in order to emit light from the LED light emitting device  100  was 300 mA. 
       FIG. 4  indicates that the red light emission intensity is decreased within a range of 600 nm to 660 nm in the emission spectrum after emission for about 100 hours as compared with the initial emission spectrum. This result indicates that the LED light emitting device  100  causes changes with time in chromaticity and emission intensity. Therefore, it is considered that K 2 SiF 6 :Mn is influenced by the light and heat from the LED element  114 . 
     Then, the LED light emitting device  10  according to the embodiment shown in  FIG. 1  was formed. In the LED light emitting device  10 , the radius of the light-transmitting resin  21  was 0.4 mm so that the red phosphor resin  22  was spaced by about 0.4 mm from the LED elements  14   a  and  14   b . Like in the comparison experiment of the LED light emitting device  100  according the comparative example, the drive current allowed to flow through the LED elements  14   a  and  14   b  in order to emit light from the LED light emitting device  10  was 300 mA, and light emission from the LED light emitting device  10  was performed for 100 hours. 
       FIG. 5  is a diagram showing an emission spectrum of the LED light emitting device  10  after emission continued for 100 hours. 
       FIG. 5  indicates that the emission intensity in the emission spectrum of the LED light emitting device  10  after emission for 100 hours is the same as in the initial emission spectrum of the LED light emitting device  100  according to the comparative example shown in  FIG. 4 . In particular, it is found that the red emission intensity is not decreased within a range of 600 nm to 660 nm. 
     Thus, it is found that when the red phosphor resin  22  containing K 2 SiF 6 :Mn is spaced by about 0.4 mm from the LED elements  14   a  and  14   b , change with time in emission intensity in the emission spectrum, particularly within the red wavelength band in the emission spectrum, can be suppressed. 
     Also, the result indicates that when the red phosphor resin  22  is disposed in a hemispherical shape on the surface of the light-transmitting resin  21  and is spaced at a substantially equal distance from the LED elements  14   a  and  14   b  covered with the red phosphor resin  22 , intensity variation with time of red light emitted from the red phosphor resin  22  due to the light from the LED elements  14   a  and  14   b  can be suppressed in the red phosphor resin  22 . 
       FIG. 6  is a diagram showing a relation between the emission time and chromaticity x in xy chromaticity coordinates in each of the LED light emitting devices  10  and  100 .  FIG. 7  is a diagram showing a relation between the emission time and chromaticity y in xy chromaticity coordinates in each of the LED light emitting devices  10  and  100 . The drive currents of both the LED light emitting devices  10  and  100  are 300 mA. 
     In  FIGS. 6 and 7 , the “current flow time” shown on the abscissa represents the emission time of each of the LED light emitting devices  10  and  100 .  FIGS. 6 and 7  show changes with time in chromaticity of the LED light emitting device  10  shown in  FIG. 10  and the LED light emitting device  100 , respectively, each using K 2 SiF 6 :Mn as the red phosphor. 
       FIGS. 6 and 7  reveal that in the LED light emitting device  100 , particularly a value of x among the x and y values significantly decreases with time. On the other hand, in the LED light emitting device  10 , both the values of x and y little change with time. 
       FIG. 8  is a diagram showing a relation between the emission time and chromaticity x in xy chromaticity coordinates in changing the drive current of the LED light emitting device  100 .  FIG. 9  is a diagram showing a relation between the emission time and chromaticity y in xy chromaticity coordinates in changing the drive current of the LED light emitting device  100 . In  FIGS. 8 and 9 , the “current flow time” shown on the abscissa represents the emission time of the LED light emitting device  100 . 
       FIGS. 8 and 9  reveal that when the drive current is a high current of each of (1) 200 mA and (5) 300 mA among (1) 200 mA, (2) 145 mA, (3) 119 mA, (4) 95 mA, and (5) 300 mA, the chromaticity x significantly changes with time, and particularly with (5) 300 mA, the chromaticity x greatly changes with time. 
     Embodiment 2 
     Embodiment 2 of the present invention is described as below on the basis of  FIG. 10 . For convenience of description, members having the same functions as the members described in the embodiment 1 are denoted by the same reference numerals, and description thereof is omitted. An embodiment of the present invention is described in detail below. 
       FIG. 10  is a sectional view showing a configuration of a LED light emitting device  11  according to Embodiment 2. The LED light emitting device (light emitting device)  11  is different from the LED light emitting device  10  in that a red/green phosphor resin (first phosphor-containing layer)  23  is provided in place of the red phosphor resin  22 , and a LED element (light emitting element)  14  is provided in place of the LED elements  14   a  and  14   b . In the LED light emitting device  11 , a red/yellow phosphor resin (first phosphor-containing layer) may be used in place of the red/green phosphor resin  23 . The LED light emitting device  11  is the same as the LED light emitting device  10  in other components. 
     The LED element  14  is connected to each of a pair of electrodes (not shown) disposed on the surface of the substrate  1  through a wire (not shown). In a plan view, the LED element  14  is disposed to be located at the center of the light-transmitting resin  21  having a hemispherical shape. The LED element  14  is, for example, a blue LED element that emits blue light with a peak wavelength of 450 nm. The emission color of the LED element  14  is not limited to this, and an ultraviolet LED element that emits ultraviolet (near-ultraviolet) with a peak wavelength of 390 nm to 420 nm may be used. 
     The light-transmitting resin  21  is disposed on the substrate  1  so as to cover the LED element  14  and have a hemispherical shape. The radius of the light-transmitting resin  21  is about 0.1 mm or more and preferably about 0.4 mm or more. 
     The red/green phosphor resin  23  contains a transparent resin such as a silicone resin as a sealing material in which a phosphor used as a red phosphor and containing a fluoride as a base material represented by (Na, K) 2 (Ge, Si, Ti)F 6 :Mn and a green phosphor excited by blue light to emit green light are dispersed. An example of the red phosphor dispersed in the red/green phosphor resin  23  is K 2 SiF 6 :Mn. 
     When the red/yellow phosphor resin is used in place of the red/green phosphor resin  23 , the red/yellow phosphor resin may contain a transparent resin such as a silicone resin as a sealing material in which a phosphor used as a red phosphor and containing a fluoride as a base material represented by (Na, K) 2 (Ge, Si, Ti)F 6 :Mn and a yellow phosphor excited by blue light to emit yellow light are dispersed. An example of the red phosphor dispersed in the red/yellow phosphor resin is K 2 SiF 6 :Mn. 
     Examples of the green phosphor or yellow phosphor constituting the red/green phosphor resin  23  or red/yellow phosphor resin include (Ba, Sr, Ca, Mg) 2 SiO 4 :Eu, (Mg, Ca, Sr, Ba)Si 2 O 2 N 2 :Eu, (Ba, Sr) 3 Si 6 O 12 N 2 :Eu, Eu-activated β-Sialon, (Sr, Ca, Ba)(Al, Ga, In) 2 S 4 :Eu, (Y, Tb, Lu, Gd) 3 (Al, Ga) 5 O 12 :Ce, Ca 3 (Sc, Mg, Na, Li) 2 Si 3 O 12 :Ce, (Ca, Sr)Sc 2 O 4 :Ce, and the like. 
     The red/green phosphor resin  23  is disposed on the surface of the light-transmitting resin  21  and has a shape along the surface of the light-transmitting resin  21 . The red/green phosphor resin  23  is formed so as to have a hemispherical shape together with the light-transmitting resin  21  disposed inside thereof. In other words, the red/green phosphor resin  23  has a shape that has a constant distance (may be referred to as a “radius” of the red/green phosphor resin  23  hereinafter) between the surface (interface with the outside) of the red/green phosphor resin  23  and a point (hereinafter, may be simply referred to a “center of the red/green phosphor resin  23 ”) on the surface of the substrate  1  and on the center axis of the red/green phosphor resin  23  (center point of the red/green phosphor resin  23  in a plan view) perpendicular to the substrate  1 . 
     Therefore, the red/green phosphor resin  23  is substantially uniformly irradiated with the light emitted from the LED element  14  as compared with a shape other than the hemispherical shape. Thus, with respect to the phosphor contained in the red/green phosphor resin  23  and containing, as the base material, a fluoride represented by (Na, K) 2 (Ge, Si, Ti)F 6 :Mn, variation of change with time in the emission intensity due to the light and heat emitted from the LED element  14  can be suppressed in the red/green phosphor resin  23 . 
     Further, the red/green phosphor resin  23  is disposed to cover only one LED element  14 , and the LED element  14  is disposed on the surface of the substrate  1  to be located at the center of the hemispherical red/green phosphor resin  23  in a plan view. Thus, the red/green phosphor resin  23  is more uniformly irradiated with the light emitted from the LED element  14  as compared with when a plurality of LED elements are disposed. Therefore, with respect to the phosphor contained in the red/green phosphor resin  23  and containing as the base material a fluoride represented by (Na, K) 2 (Ge, Si, Ti)F 6 :Mn, variation of change with time in the emission intensity due to the light emitted from the LED element  14  can be more suppressed in the red/green phosphor resin  23 . 
     In addition, as in the red/green phosphor resin  23 , when a green phosphor of a type different from the phosphor containing as the base material a fluoride represented by (Na, K) 2 (Ge, Si, Ti)F 6 :Mn is contained, the amount of the phosphor containing as the base material a fluoride represented by (Na, K) 2 (Ge, Si, Ti)F 6 :Mn can be decreased as compared with a phosphor-containing layer containing only the phosphor containing as the base material a fluoride represented by (Na, K) 2 (Ge, Si, Ti)F 6 :Mn. Therefore, variation of change with time in the emission intensity can be further suppressed in the red/green phosphor resin  23 . 
     In addition, the red/green phosphor resin  23  is spaced from the LED element  14  because the re/green phosphor resin  23  does not directly seal the LED element  14  and is disposed on the surface of the light-transmitting resin  21  that seals the LED element  14 . The red/green phosphor resin  23  is spaced by about 0.1 mm or more, preferably about 0.4 mm or more, from the LED element  14 . Therefore, with respect to the phosphor contained in the red/green phosphor resin  23  and containing as the base material a fluoride represented by (Na, K) 2 (Ge, Si, Ti)F 6 :Mn, change with time in the emission intensity due to the light emitted from the LED element  14  can be more securely suppressed. 
     EXAMPLE 2 
     A LED light emitting device  11  shown in  FIG. 10  was formed and confirmed with respect to changes with time in an emission spectrum by the same method as in Example 1. 
     In the LED light emitting device  11 , the radius of a light-transmitting resin  21  was 0.4 mm so that a red/green phosphor resin  23  was spaced by about 0.4 mm from a LED element  14 . Like in Example 1, the drive current for emitting light from the LED light emitting device  11  was 300 mA, and light emission from the LED light emitting device  11  was performed for 100 hours. As a result, substantially the same emission spectrum as that shown in  FIG. 5  was obtained. 
     It was thus found that the emission intensity in the emission spectrum of the LED light emitting device  11  after emission continued for 100 hours is the same as in the initial emission spectrum of the LED light emitting device  100  according to the comparative example shown in  FIG. 4 . In particular, it was found that the red emission intensity is not decreased within a range of 600 nm to 660 nm. 
     Thus, it was found that even in the LED light emitting device  11 , when the red/green phosphor resin  23  containing K 2 SiF 6 :Mn is spaced by about 0.4 mm from the LED element  14 , change with time in the emission intensity in the emission spectrum, particularly within the red wavelength band in the emission spectrum, can be suppressed. 
     Also, the result indicates that when the red/green phosphor resin  23  is disposed to have a hemispherical shape on the surface of the light-transmitting resin  21  and is spaced at a substantially equal distance from the LED element  14  covered with the red/green phosphor resin  23 , intensity variation with time of red light emitted from the red/green phosphor resin  23  due to light from the LED element  14  can be suppressed in the red/green phosphor resin  23 . 
     Embodiment 3 
     Embodiment 3 of the present invention is described as below on the basis of  FIG. 11 . For convenience of description, members having the same functions as the members described in Embodiments 1 and 2 are denoted by the same reference numerals, and description thereof is omitted. An embodiment of the present invention is described in detail below. 
       FIG. 11  is a sectional view showing a configuration of a LED light emitting device  12  according to Embodiment 3. The LED light emitting device (light emitting device)  12  is different from the LED light emitting device  11  in that a red phosphor resin (first phosphor-containing layer)  24  and a green phosphor resin (second phosphor-containing layer)  25  are provided in place of the red phosphor resin  22 . The LED light emitting device  12  is the same as the LED light emitting device  11  in other components. 
     The red phosphor resin  24  contains a transparent resin such as a silicone resin as a sealing material in which a phosphor used as a red phosphor and containing a fluoride as a base material represented by (Na, K) 2 (Ge, Si, Ti)F 6 :Mn is dispersed. An example of the red phosphor dispersed in the red phosphor resin  24  is K 2 SiF 6 :Mn. The red phosphor resin  24  is disposed on the surface of the light-transmitting resin  21  and has a shape along the surface of the light-transmitting resin  21 . The red phosphor resin  24  is formed so as to have a hemispherical shape together with the light-transmitting resin  21  disposed inside thereof. In other words, the red phosphor resin  24  has a shape that has a constant distance (may be referred to as a “radius” of the red phosphor resin  24  hereinafter) between the surface (interface with the green phosphor resin  25 ) of the red phosphor resin  24  and a point (hereinafter, may be simply referred to a “center of the red phosphor resin  24 ”) on the surface of the substrate  1  and on the center axis of the red phosphor resin  24  (center point of the red phosphor resin  24  in a plan view) perpendicular to the substrate  1 . 
     Therefore, the red phosphor resin  24  is substantially uniformly irradiated with the light emitted from the LED element  14  as compared with a shape other than the hemispherical shape. Thus, with respect to the phosphor contained in the red phosphor resin  24  and containing as the base material a fluoride represented by (Na, K) 2 (Ge, Si, Ti)F 6 :Mn, variation of change with time in the emission intensity due to the light and heat emitted from the LED element  14  can be suppressed in the red phosphor resin  24 . 
     The green phosphor resin  25  contains a transparent resin such as a silicone resin as a sealing material in which the green phosphor that emits green light by the light emitted from the LED element  14  is dispersed. The green phosphor resin  25  is disposed on the surface of the red phosphor resin  24  to have a shape along the surface of the red phosphor resin  24 . The green phosphor resin  25  is formed so as to have a hemispherical shape together with the light-transmitting resin  21  and the red phosphor resin  24  disposed inside thereof. In other words, the green phosphor resin  25  has a shape having a constant distance (may be referred to as a “radius” of the green phosphor resin  25  hereinafter) between the surface (interface with the outside) of the green phosphor resin  25  and a point (hereinafter, may be simply referred to a “center of the green phosphor resin  25 ”) on the surface of the substrate  1  and on the center axis of the green phosphor resin  25  (center point of the green phosphor resin  25  in a plan view) perpendicular to the substrate  1 . The shape of the green phosphor resin  25  is not limited to the hemispherical shape and may be another shape. 
     Further, the red phosphor resin  24  is disposed to cover only one LED element  14 , and the LED element  14  is disposed on the surface of the substrate  1  to be located at the center of the hemispherical red phosphor resin  24  in a plan view. Thus, the red phosphor resin  24  is more uniformly irradiated with the light emitted from the LED element  14  as compared with when a plurality of LED elements are disposed. Therefore, with respect to the phosphor contained in the red phosphor resin  24  and containing as the base material a fluoride represented by (Na, K) 2 (Ge, Si, Ti)F 6 :Mn, variation of change with time in the emission intensity due to the light emitted from the LED element  14  can be more suppressed in the red phosphor resin  24 . 
     Also, the red phosphor resin  24  does not directly seal the LED element  14 . The red phosphor resin  24  is spaced from the LED element  14  because the red phosphor resin  24  is disposed on the surface of the light-transmitting resin  21  that seals the LED element  14 . Therefore, it is possible to improve the effect of suppressing change with time in emission intensity of K 2 SiF 6 :Mn contained in the red phosphor resin  24  due to the light emitted from the LED element  14 . 
     The red phosphor resin  24  is spaced by about 0.1 mm or more, preferably about 0.4 mm or more, from the LED element  14 . Therefore, a decrease in emission intensity of the red phosphor resin  24  can be more securely suppressed. 
     Also, the LED light emitting device  11  includes two phosphor-containing layers including the red phosphor resin  24  and the green phosphor resin  25  which contain different phosphors. Therefore, the thickness of the red phosphor resin  24  containing the phosphor containing, as the base material, a fluoride represented by (Na, K) 2 (Ge, Si, Ti)F 6 :Mn can be decreased as compared with a LED light emitting device including one red phosphor-containing layer. Therefore, with resect to the phosphor contained in the red phosphor resin  24  and containing as the base material a fluoride represented by (Na, K) 2 (Ge, Si, Ti)F 6 :Mn, variation of change with time in the emission intensity due to the light emitted from the LED element  14  can be more suppressed in the red phosphor resin  24  as compared with a LED light emitting device including one phosphor-containing layer. 
     Also, the LED light emitting device  12  has the effect of preventing scattering of the red phosphor from the red phosphor resin  24  because the red phosphor resin  24  is disposed between the light-transmitting resin  21  and the green phosphor resin  25 . In addition, the supply of moisture to the red phosphor resin  24  is cut off, and thus reaction of the red phosphor with moisture can be suppressed, thereby causing the effect of suppressing the occurrence of hydrofluoric acid. 
     EXAMPLE 3 
     A LED light emitting device  12  shown in  FIG. 11  was formed and confirmed with respect to changes with time in an emission spectrum by the same method as in Examples 1 and 2. 
     In the LED light emitting device  12 , the radius of a light-transmitting resin  21  was 0.4 mm, and further a red phosphor resin  24  was disposed on the surface of the light-transmitting resin  21 . Thus, the red phosphor resin  24  was spaced by 0.4 mm or more from a LED element  14 . Like in Examples 1 and 2, the drive current for emitting light from the LED light emitting device  12  was 300 mA, and light emission from the LED light emitting device  12  was performed for 100 hours. As a result, substantially the same emission spectrum as that shown in  FIG. 5  could be obtained. 
     It was thus found that the emission intensity in the emission spectrum of the LED light emitting device  12  after emission continued for 100 hours is the same as in the initial emission spectrum of the LED light emitting device  100  according to the comparative example shown in  FIG. 4 . In particular, it was found that the red emission intensity is not decreased within a range of 600 nm to 660 nm. 
     Thus, it was found that even in the LED light emitting device  12 , when the red phosphor resin  24  containing K 2 SiF 6 :Mn is spaced by 0.4 mm or more from the LED element  14 , change with time in the emission intensity in the emission spectrum, particularly within the red wavelength band in the emission spectrum, can be suppressed. 
     Also, the result indicates that when the red phosphor resin  24  is disposed on the surface of the green phosphor resin  25  to have a hemispherical shape and is spaced at a substantially equal distance from the LED element  14  covered with the red phosphor resin  24 , intensity variation with time of red light emitted from the red phosphor resin  24  due to the light from the LED element  14  can be suppressed in the red phosphor resin  24 . 
     MODIFIED EXAMPLE 
       FIG. 13  is a sectional view showing a configuration of a LED light emitting device  12   a  according to a modified example of the LED light emitting device  12  shown in  FIG. 11 . 
     The LED light emitting device (light emitting device)  12   a  shown in  FIG. 13  is different from the LED light emitting device  12  in that a reflector (reflecting member)  17  is provided. The LED light emitting device  12   a  is the same as the LED light emitting device  12  with respect to other components. 
     The reflector  17  is disposed on the surface of the substrate  1  to surround the LED element  14 , the light-transmitting resin  21 , the red phosphor resin  24 , and the green phosphor resin  25 . 
     An example of a material constituting the reflector  17  is a white resin material, but the material is not limited to this and a material generally used for the reflecting member can be used. 
     In the LED light emitting device (light emitting device)  12   a , light emitted from the LED element  14 , the red phosphor resin  24 , and the green phosphor resin  25  is reflected by the reflector  17  in the direction of emission (upward direction in  FIG. 13 ) of the LED light emitting device  12   a . Therefore, light with high luminance can be emitted as compared with the LED light emitting device  12  not including the reflector  17 . 
     SUMMARY 
     A light emitting device (the LED light emitting device  10 ,  11 , or  12 ) in aspect  1  of the present invention includes a substrate  1 , a light emitting element (the LED element  14   a ,  14   b , or  14 ) disposed on the substrate  1 , a sealing resin (the light-transmitting resin  21 ) disposed on the substrate  1  to seal the light emitting element, and a first phosphor-containing layer (the red phosphor resin  22 ,  24 , or the red/green phosphor resin  23 ) containing at least a phosphor as a red phosphor containing, as a base material, a fluoride represented by (Na, K) 2 (Ge, Si, Ti)F 6 :Mn, the first phosphor-containing layer being disposed directly or indirectly on the surface of the sealing resin so as to cover the light emitting element and have a hemispherical shape. 
     In the configuration described above, the first phosphor-containing resin is disposed directly or indirectly on the surface of the sealing resin. Therefore, the first phosphor-containing resin can be spaced from the LED element with a space corresponding to at least the sealing resin disposed thereon. Thus, change with time in the emission intensity of the red phosphor due to the light and heat emitted from the LED element can be suppressed. In addition, the first phosphor-containing layer has a hemispherical shape, and thus, variation of the change with time in the emission intensity of the red phosphor due to the light and heat emitted from the light emitting element can be suppressed in the first phosphor-containing layer. 
     In a light emitting device in aspect  2  of the present invention, in the aspect  1 , the sealing resin has a hemispherical shape, and the radius of the sealing resin is preferably about 0.1 mm or more. In the configuration described above, change with time in the emission intensity of the red phosphor due to the light and heat emitted from the LED element can be securely suppressed. 
     In a light emitting device in an aspect 3 of the present invention, in the aspect 1 or 2, the first phosphor-containing resin (the red/green phosphor resin  23 ) preferably further contains a phosphor that emits light of a color different from the red phosphor. In the configuration, the content of the red phosphor can be decreased, variation of the change with time in the emission intensity of the red phosphor due to the light and heat emitted from the LED element  14  can be more suppressed in the first phosphor-containing layer. 
     In a light emitting device in aspect 4 of the present invention, in the aspects 1 to 3, a second phosphor-containing layer (the green phosphor resin  25 ) containing a phosphor that emits light of a color different from that of the red phosphor is provided, and the second phosphor-containing layer is preferably disposed on the surface of the first phosphor-containing layer. In the configuration, the thickness of the first phosphor-containing layer can be decreased. Thus, the content of the red phosphor can be decreased, and variation of the change with time in the emission intensity of the red phosphor due to the light and heat emitted from the LED element can be more suppressed in the first phosphor-containing layer. 
     In a light emitting device in aspect 5 of the present invention, in the aspects 1 to 4, the red phosphor is preferably a phosphor containing potassium hexafluorosilicate as a base material. Therefore, the red phosphor can be formed as an aspect. 
     In a light emitting device according to an aspect of the present invention, even in the aspects described above, the drive current allowed to flow through the light emitting element in order to emit light from the light emitting element is preferably 200 mA or more. Therefore, even when a high current is allowed to flow through the light emitting element, change with time in emission intensity of the red phosphor due to the light and heat emitted from the light emitting element and variation of the change with time in the emission intensity can be suppressed in the first phosphor-containing layer. 
     In a light emitting device according to an aspect of the present invention, in the aspects described above, the light-emitting element is preferably disposed to be located at the center of the first phosphor-containing layer in a plan view. In the configuration, variation of the change with time in the emission intensity of the red phosphor due to the light and heat emitted from the light emitting element can be more suppressed in the first phosphor-containing layer. 
     In a light emitting device according to an aspect of the present invention, in the aspects described above, the sealing resin has a hemispherical shape, and the radius of the sealing resin is preferably 0.4 mm or more. In the configuration, change with time in the emission intensity of the red phosphor can be further securely suppressed. 
     The present invention is not limited to the embodiments described above and various modifications can be made within the scope described in the claims. The technical scope of the present invention also includes embodiments made by properly combining the technical methods disclosed in different embodiments. Further, a new technical feature can be formed by combining the technical methods disclosed in the respective embodiments. 
     INDUSTRIAL APPLICABILITY 
     The present invention can be used for a light emitting device. 
     REFERENCE SIGNS LIST 
       1  SUBSTRATE 
       2 ,  3  ELECTRODE 
       10 ,  11 ,  12  LED LIGHT EMITTING DEVICE (LIGHT EMITTING DEVICE) 
       14 ,  14 A,  14 B LED ELEMENT (LIGHT EMITTING ELEMENT) 
       15  WIRE 
       21  LIGHT-TRANSMITTING RESIN (SEALING RESIN) 
       22  RED PHOSPHOR RESIN (FIRST PHOSPHOR-CONTAINING LAYER) 
       23  RED/GREEN PHOSPHOR RESIN (FIRST PHOSPHOR-CONTAINING LAYER) 
       24  RED PHOSPHOR RESIN (FIRST PHOSPHOR-CONTAINING LAYER) 
       25  GREEN PHOSPHOR RESIN (SECOND PHOSPHOR-CONTAINING LAYER)