JP5679435B2 - Light emitting device - Google Patents

Description

  The present invention relates to a light emitting device.

  Conventionally, as a light-emitting device using a light-emitting element such as an LED element, one in which phosphor particles are contained in a transparent material such as a sealing material for a light-emitting element is known. However, when phosphor particles are contained in a resin, glass or the like, the specific gravity of the transparent material and the phosphor particles is different, so that it is difficult to uniformly disperse the phosphor particles in the transparent material. As a result, there is a problem that unevenness of color occurs in the light extracted from the transparent material.

  In order to solve this problem, it has been proposed by the present inventors to use fluorescent glass containing rare earth ions as the emission center without using phosphor particles (see, for example, Patent Document 1). According to this fluorescent glass, uneven color of light can be reduced, and the manufacturing process can be reduced because the mixing step of the phosphor particles and the transparent material is not necessary.

Pamphlet of International Publication No. 2010/055831

  By the way, a fluorescent glass having a rare earth ion as a light emission center as in Patent Document 1 is different in optical behavior from a glass in which phosphor particles are dispersed and a transparent glass not containing a rare earth ion. Since the glass in which the phosphor particles are dispersed is reflected and refracted at the interface between the phosphor particles and the glass, the optical behavior is completely different from that of the fluorescent glass that is not reflected and refracted between the rare earth ions and the glass matrix. Different. In addition, transparent glass that does not contain rare-earth ions is basically fluorescent light in which the light in the glass basically travels straight, so that there is absorption of excitation light in the rare-earth ions and isotropic emission of wavelength-converted light. Optical behavior is completely different from glass. However, the optical behavior of fluorescent glasses containing rare earth ions has not been clarified.

  This invention is made | formed in view of the said situation, The place made into the objective is to provide the light-emitting device using the optical behavior of fluorescent glass.

  In order to achieve the above object, in the present invention, a light source, an incident surface that includes a rare earth ion that forms a light emission center in a matrix, and incident light that is emitted from the light source, and an emission surface that emits wavelength-converted light are provided. And a glass phosphor comprising: a light emitting device having an inclined surface that is inclined with respect to the optical axis so that at least a part of a side surface of the glass phosphor extends from the incident side toward the emission side. The

  In the light emitting device, a transparent medium that is adjacent to the outside of the inclined surface and transparent to the wavelength-converted light is disposed, and the light incident on the inclined surface in the glass phosphor is the glass phosphor. And may be totally reflected by the difference in the refractive index of the light transmissive material.

  In the light emitting device, when the inclination angle of the inclined surface is increased from a state parallel to the optical axis, the emission intensity on the optical axis becomes the highest when the inclination angle is equal to or less than a predetermined critical angle, and the inclination angle is predetermined. When the critical angle is exceeded, the position with the highest emission intensity may be separated from the optical axis.

  In the light emitting device, an inclination angle of the inclined surface may be equal to or less than the predetermined critical angle.

  In the light emitting device, an inclination angle of the inclined surface may exceed the predetermined critical angle.

  In the light emitting device, the light source may be a semiconductor light emitting element, and the glass phosphor may seal the semiconductor light emitting element.

  In the light emitting device, the emission center of the glass phosphor may be Yb ions and Nd ions.

  According to the present invention, the optical behavior of fluorescent glass can be utilized.

FIG. 1A is a schematic cross-sectional view of a light-emitting device showing an embodiment of the present invention. FIG. 1B is a schematic cross-sectional view of a light emitting device showing a modification. FIG. 1C is a schematic cross-sectional view of a light emitting device showing a modification. FIG. 1D is a schematic cross-sectional view of a light emitting device showing a modification. FIG. 2 is a schematic cross-sectional view of a light emitting device showing a modification. FIG. 3 is a schematic cross-sectional view of a light emitting device showing a modification. FIG. 4 is a schematic cross-sectional view of a light-emitting device showing an example. FIG. 5 is a schematic cross-sectional view of a light emitting device showing a comparative example. FIG. 6 is a graph relating to the light emitting devices of the example and the comparative example, in which the horizontal axis represents the current of the LED element, and the vertical axis represents the output of light emitted from the light emitting device. FIG. 7 is a graph regarding the comparative example and the light emitting devices of Examples 1 to 3, in which the horizontal axis is the horizontal distance from the optical axis and the vertical axis is the emission intensity. FIG. 8 is a graph relating to a light-emitting device in which the horizontal axis is the inclination angle and the vertical axis is the emission intensity. FIG. 9 is a schematic cross-sectional view of a light-emitting device showing an example. FIG. 10 is a graph regarding the light emitting devices of Examples 1 to 3 in which the horizontal axis is the horizontal distance from the optical axis, the vertical axis is the emission intensity, and the metal film is formed on the side surface.

  FIG. 1A is a schematic cross-sectional view of a light-emitting device showing an embodiment of the present invention.

  As shown in FIG. 1A, the light emitting device 1 has a case 2 in which a concave portion 2a having an upper opening is formed, and an LED element 3 is flip-chip mounted in the concave portion 2a. The recess 2a is formed by a reflector 2b surrounding the LED element 3, and a first lead 4 and a second lead 5 made of metal for supplying power to the LED element 3 are arranged at the bottom of the recess 2a. In addition, a sealing resin 6 that seals the LED element 3 is filled in the lower portion of the recess 2a. Further, a fluorescent glass 7 is disposed on the upper side of the sealing resin 6 in the recess 2a.

  The light emitting device 1 can emit infrared light of about 850 nm to 1220 nm. Since this wavelength region is highly permeable to a living body, it is suitable for use as a light source in, for example, the medical field or the living body observation field. In particular, since the wavelength region of 900 nm to 1000 nm is covered, there is an absorption spectrum due to fat, moisture, etc., which is useful as a light source in the agricultural / food field.

  The case 2 is made of resin and has a substantially rectangular parallelepiped shape as a whole. The leads 4 and 5 form part of the bottom surface of the recess 2a, and the resin of the case 2 forms the other part of the bottom surface of the recess 2a. The inner peripheral surface of the reflector portion 2b is formed so as to expand upward and has a smooth curved surface. In the present embodiment, the reflector portion 2b is formed in a circular shape in plan view.

  A metal film 8 is formed on the inner peripheral surface of the reflector portion 2b. The metal film 8 is made of a metal having a relatively high reflectance such as aluminum. The metal film 8 is formed, for example, by vapor deposition.

  The first lead 4 and the second lead 5 are made of, for example, a conductive metal plated with silver. The first lead 4 and the second lead 5 are formed with a predetermined thickness dimension and width dimension, and their longitudinal ends are located in the recess 2 a of the case 2. The first lead 4 and the second lead 5 extend to the outside of the case 2 and are electrically connected to an external connection terminal (not shown).

  The LED element 3 includes a substrate, a semiconductor layer, and a p electrode and an n electrode connected to the semiconductor layer. The p electrode and the n electrode are electrically connected to the leads 4 and 5, respectively. In the present embodiment, the LED element 3 is a flip chip type, and the p electrode is connected to the first lead 4 and the n electrode is connected to the second lead 5.

In the present embodiment, the substrate is made of sapphire, and the semiconductor layer is represented by an expression of In _x Al _y Ga _1-xy N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1). Made of semiconductor. For example, the LED element 3 emits light having a peak wavelength of 585 nm and a half width of 50 nm.

  The sealing resin 6 is filled in the recess 2b after the LED elements 3 are mounted on the leads 4 and 5, respectively. The material of the sealing resin 6 is arbitrary, and for example, a silicone resin or an epoxy resin is used.

  The fluorescent glass 7 is disposed on the upper side of the sealing resin 6, and has an incident surface 7 a on which the light of the LED element 3 enters through the sealing resin 6, and an output surface 7 b that emits the wavelength-converted light. doing. In the present embodiment, the incident surface 7 a is formed in a flat circular shape and is in contact with the upper surface of the sealing resin 6. Further, the emission surface 7b is formed in a flat circular shape, and the height is matched with the upper surface of the case 2. The entrance surface 7a and the exit surface 7b are concentric in a plan view, and the optical axis 7d of the fluorescent glass 7 is a normal line passing through the centers of the entrance surface 7a and the exit surface 7b. Here, the optical axis 7d indicates a virtual light beam that is representative of a light beam that passes through the entire system in the optical system. In many cases, it coincides with the rotational symmetry axis of a lens, an optical element, etc., and for example, a single lens is a straight line connecting the centers of curvature of two front and rear surfaces.

  The fluorescent glass 7 has an inclined surface that is inclined with respect to the optical axis 7d so that the side surface 7c expands from the incident side toward the emission side. In the fluorescent glass 7 in which rare earth ions are the emission center, when the inclination angle of the inclined surface is increased from a state parallel to the optical axis 7d, the emission intensity on the optical axis 7d is highest when the inclination angle is less than a predetermined critical angle. Thus, when the tilt angle exceeds a predetermined critical angle, the position with the highest light emission intensity moves away from the optical axis 7d. In the present embodiment, the inclination angle of the side surface 7c is set to a critical angle or less. The critical angle changes depending on conditions such as the refractive index of the fluorescent glass 7. In the present embodiment, the inclination angle of the side surface 7c is set to 30 degrees in consideration of the critical angle.

  Further, the side surface 7c is formed so as to be spaced apart from the metal film 8 on the surface of the reflector portion 2b at a constant interval. That is, the space | gap 9 is formed between the side surface 7c of the fluorescent substance glass 7, and the reflector part 2b. The air gap 9 is filled with air as a transparent medium. The refractive index of air is lower than the refractive index of the fluorescent glass 7.

  The fluorescent glass 7 has a matrix made of glass and a light emission center included in the matrix. The “emission center” here is a structure that exists in the host material and emits light, but the host material means a material that substantially constitutes one material, and is made of a transparent material such as resin or glass. This is different from the phosphor particles contained in the material. That is, when phosphor particles are contained in a transparent material made of resin, glass, etc., the transparent material made of resin, glass, etc. and the phosphor particles are separate materials and constitute one material. I cannot say that.

Specifically, the base of the fluorescent glass 7 is made of Bi ₂ O ₃ —B ₂ O ₃ based glass, and the emission centers are Yb ³⁺ and Nd ³⁺ . The fluorescent glass 7 emits infrared light of 900 nm to 1100 nm when excited by the light emitted from the LED element 3. The fluorescent glass 7 is produced by mixing and melting Yb ₂ O ₃ powder, Nd ₂ O ₃ powder, Bi ₂ O ₃ powder, and H ₃ BO ₃ powder, and then cooling. Here, since Bi ³⁺ is reduced when it exceeds 1000 ° C., when it is heated to 1000 ° C. and melted, Sb ₂ O ₃ powder may be added to suppress the reducing action of Bi ^3+. . The concentration of _Yb 2 _{O 3} is less 4.0 mol%, and, if the concentration of _Nd 2 _{O 3} is less 5.0 mol%, fluorescent glass 7 has been confirmed that melts at 1000 ° C..

  This fluorescent glass 7 is excited from 450 nm to 800 nm. Therefore, the LED element 3 can excite the fluorescent glass 7 as long as it emits light in a wavelength region of 450 nm to 800 nm. Further, the excitation spectrum of the fluorescent glass 7 has a plurality of peaks, and in particular, the excitation efficiency is around 530 nm, 585 nm, 685 nm, and 750 nm. Among these, the excitation efficiency in the vicinity of 585 nm is the most excellent, and the peak wavelength of the LED element 3 of the present embodiment is 585 nm. Therefore, the LED element 3 and the fluorescent glass 7 are excellent in excitation efficiency.

  The light emitting device 1 configured as described above emits yellow light having a peak wavelength of 585 nm and a half width of 50 nm from the LED element 3 when a voltage is applied to the leads 4 and 5. Light emitted from the LED element 3 enters the fluorescent glass 7 from the incident surface 7 a through the sealing resin 6. The yellow light that has entered the fluorescent glass 7 is wavelength-converted into infrared light within the fluorescent glass 7 and then emitted from the emission surface 7b. For example, the infrared light has a peak wavelength of 1020 nm and a full width at half maximum of 100 nm.

  Here, the rare earth ions forming the emission center are uniformly contained in the base glass inside the fluorescent glass 7, and the wavelength conversion is similarly performed in the entire region inside the glass made only of the fluorescent material. That is, unlike the conventional light-emitting device in which the phosphor is included in the transparent material as a particle, color unevenness does not occur depending on the particle distribution state.

  Further, when excitation light is incident on the rare earth ions in the fluorescent glass 7, the excitation light is absorbed by the rare earth ions, and wavelength converted light is emitted radially from the rare earth ions. This is an optical behavior that is completely different from those of conventional materials in which a phosphor is contained as a particle in a transparent material and transparent glass that does not contain rare earth ions. That is, when the phosphor particles are dispersed, light is reflected and refracted at the interface between the phosphor particles and the transparent material, so that a light diffusing action is generated in addition to the wavelength converting action. If rare earth ions are not included, the light in the glass basically goes straight.

  Since the side surface 7c of the fluorescent glass 7 is inclined with respect to the optical axis 7d, the intensity of outgoing light emitted from the outgoing surface 7b of the fluorescent glass 7 can be improved. This is based on the specific optical behavior of the fluorescent glass 7 having the emission center of rare earth ions, and is a light emitting device 1 utilizing the optical behavior.

  If the side surface 7c is up to the critical angle, the light emission intensity on the optical axis 7d is the highest. However, if the side surface 7c is tilted beyond the critical angle with respect to the optical axis 7d, the peak of the light emission intensity is the optical axis 7d. Keep away from. Therefore, if importance is attached to the magnitude of the light emission intensity directly above the optical axis 7d, a critical angle or less is preferable, but more uniform light distribution characteristics such that sufficient intensity can be obtained even at a position separated from the optical axis 7d. It is preferable that the critical angle is exceeded. Therefore, even if the side surface 7d is inclined with respect to the optical axis 7d so as to exceed the critical angle, the optical behavior of the fluorescent glass 7 can be utilized.

  Further, according to the light emitting device 1 of the present embodiment, optical design can be easily and easily performed by the inclination angle of the side surface 7c. As in the past, when phosphor particles are dispersed in a transparent material, the optical behavior changes depending on the dispersed state of the phosphor particles in addition to the shape of the transparent material, so the design is not easy and is manufactured. The optical characteristics vary depending on the light emitting device.

  Further, since the air gap 9 is provided outside the side surface 7c and air as a transparent medium having a low refractive index is arranged adjacent to the outside of the inclined surface, the light enters the side surface 7c in the glass phosphor 7. The light is totally reflected by the difference in refractive index between the glass phosphor 7 and air. Thereby, compared with the case where a metal film is directly formed on the side surface 7c, for example, the light extraction efficiency can be increased.

  Furthermore, since the metal film 8 is formed on the surface of the reflector portion 2b, the light leaking from the glass phosphor 7 to the gap 9 is reflected using the metal film 8 and is incident again on the glass phosphor 7. Can do. Thereby, the light extraction efficiency can be further increased.

In the above-described embodiment, the entire side surface 7c is an inclined surface. However, if at least a part of the side surface 7c is an inclined surface, the light extraction efficiency can be improved. In addition, although the inclination of the side surface 7c is 30 degrees with respect to the optical axis 7d, the inclination angle is arbitrary. In addition, the improvement of the light extraction efficiency due to the inclination becomes remarkable at 15 degrees or more in the case of a combination of the above materials.
Moreover, in the said embodiment, although the side surface 7c of the fluorescent glass 7 and the surface of the reflector part 2b of the case 2 incline at the same angle, the side surface 7c and the surface of the reflector part 2b are illustrated. The inclination angle is arbitrary. Further, the reflector portion 2b may be parallel to the optical axis without being inclined.
Furthermore, in the said embodiment, although the state where the side surface 7c of the fluorescent glass 7 and the reflector part 2b of the case 2 are comparatively close is illustrated, it does not interfere even if both are largely separated. . By ensuring a sufficient distance between the two, the number of reflections on the surface of the reflector 2b until the light leaking into the gap 9 is extracted from the light emitting device 1 can be reduced.

In the above embodiment, the incident surface 7a is flat, but may be curved as shown in FIG. 1B, for example. In FIG. 1B, it is formed in a semi-elliptical shape surrounding the LED element 3.
Further, for example, as shown in FIG. 1C, the incident surface 7a may be composed of a plurality of flat surfaces. In FIG. 1C, the incident surface 7 a opens downward and forms a regular hexahedron together with the bottom of the recess 2 a of the case 2.
Furthermore, for example, as shown in FIG. 1D, the LED element 3 may be directly sealed with a fluorescent glass 7. In this case, the incident surface 7 a is a contact surface with the LED element 3 in the fluorescent glass 7.
Moreover, in the said embodiment, although the output surface 7b of the glass fluorescent substance 7 was shown as a flat surface, of course, it is good also as a curved surface. For example, the glass phosphor 7 may be a lens in which both the entrance surface 7a and the exit surface 7b are curved.

  Further, although the metal film 8 is formed on the surface of the reflector portion 2b, the metal film 8 may not be formed as shown in FIG. In this case, light is reflected on the surface of the reflector 2b.

  In the above embodiment, the transparent medium adjacent to the side surface 7 of the fluorescent glass 7 is air. However, a transparent medium other than gas may be adjacent. For example, as shown in FIG. 3, the transparent resin 9 a may be adjacent to the side surface 7. In short, a transparent medium having a refractive index lower than that of the glass phosphor 7 may be disposed.

Moreover, in the said embodiment, although what used Sb2O3-B2O3 type | system | group boric acid type glass as a base material of the fluorescent glass 7 was shown, you may use phosphoric acid type glass and fluoride glass. Specifically, low melting point glass such as Bi ₂ O ₃ —GeO ₂ glass, ZnO—B ₂ O ₃ glass, CaO—B ₂ O ₃ glass, and CaO—P ₂ O ₅ glass is exemplified. Can do.

  Furthermore, although Yb ions and Nd ions are exemplified as the emission center of the fluorescent glass 7 of the above embodiment, rare earth ions such as Tm ions, Er ions, Dy ions, and Pr ions can be used. Since the rare earth ions have different emission wavelengths, the rare earth ions may be selected according to the use of the light emitting device 1.

  Furthermore, in consideration of the light distribution characteristics of the LED element 3, the rare earth ion concentration and the composition of the base glass can be appropriately changed so that the desired light distribution characteristics in the light emitting device 1 can be realized.

  In the above embodiment, an LED element is used as a light source. However, another light emitting element such as an LD element may be used. For example, a white LED in which a phosphor and an LED element are integrated is used. Other specific details may be changed as appropriate.

  Hereinafter, examples and comparative examples of the present invention will be described with reference to FIGS. FIG. 4 is a schematic cross-sectional view of a light-emitting device showing an example, and FIG. 5 is a schematic cross-sectional view of a light-emitting device showing a comparative example.

As shown in FIG. 4, as the light emitting device 101 of the first embodiment, a glass having a white LED 103 as a light source, an incident surface 107a on which light emitted from the white LED 103 is incident, and an output surface 107b that emits wavelength-converted light. A phosphor was prepared. The entrance surface 107a and the exit surface 107b are each a flat circle and are parallel to each other. That is, the optical axis 107d of the fluorescent glass 107 is a normal passing through the centers of the circles of the entrance surface 107a and the exit surface 107b. Further, the side surface 107c of the glass phosphor 107 is inclined by 30 degrees with respect to the optical axis over the entire surface. The base of the fluorescent glass 107 is made of Bi ₂ O ₃ —B ₂ O ₃ glass, and the emission centers are Yb ³⁺ and Nd ³⁺ . A transparent resin 106 was filled between the white LED 103 and the fluorescent glass 107.

  In addition, as shown in FIG. 5, a light emitting device 201 of a comparative example was prepared that includes a fluorescent glass 207 having a shape different from that of the light emitting device 101 of Example 1. In this fluorescent glass 207, the exit surface 207b has the same shape as that of the first embodiment, but the entrance surface 207a is formed in the same shape as the exit surface 207b, and the side surface 207c is not inclined with respect to the optical axis 207d. Other configurations are the same as those of the first embodiment.

Here, also the light emitting device 201 also comparative examples emitting device 101 of Example 1, a phosphor glass 107, _Yb 2 _{O 3} and 1.0 mol%, 4.0 mol% of _Nd 2 _{O 3,} a _Bi 2 _{O 3 47.0mol%,} B 2 _{O 3} to 47.0mol%, to prepare a _Sb 2 _{O 3} as 1.0 mol%.

  FIG. 6 is a graph relating to the light emitting devices of the example and the comparative example, in which the horizontal axis represents the current of the LED element, and the vertical axis represents the output of light emitted from the light emitting device. The light output was measured at a wavelength of 1020 nm. In the measurement, the light emitting devices of Example 1 and Comparative Example were fixed in a metal case having an opening, and the amount of light was measured so that light did not leak outside from the metal case. The light amount was measured in a predetermined range with the optical axis as the center.

  As shown in FIG. 6, the light emitting device 101 of Example 1 has higher light emission intensity than the light emitting device 201 of the comparative example. Specifically, the light emission intensity is about 1.8 times regardless of the magnitude of the current. Accordingly, it is understood that the emission intensity is improved when the side surface of the fluorescent glass is inclined with respect to the optical axis.

  Furthermore, in addition to the fluorescent glass 107 of Example 1 and the fluorescent glass 207 of the comparative example, the fluorescent glass of Example 2 having a side surface inclination angle of 15 degrees and the fluorescent glass of Example 3 having 45 degrees were prepared. And with the fluorescent glass single-piece | unit, light injected into the entrance plane of Examples 1-3 and the fluorescent glass of a comparative example, and measured the emitted light intensity. Light emitted from the LED element sufficiently separated from the fluorescent glass was incident on the incident surface through a circular hole formed in a metal plate-like member disposed immediately before the fluorescent glass.

  FIG. 7 is a graph regarding the comparative example and the light emitting devices of Examples 1 to 3, in which the horizontal axis is the horizontal distance from the optical axis and the vertical axis is the emission intensity. As shown in FIG. 7, when the inclination angle of the side surface of the fluorescent glass is 0 degree (comparative example), 15 degrees (example 2), and 30 degrees (example 1), there is a peak of emission intensity on the optical axis. . However, in the case of 45 degrees (Example 3), the peak on the optical axis did not reach the maximum intensity, and the peak of the emission intensity appeared at a position away from the optical axis.

  FIG. 8 is a graph relating to a light-emitting device in which the horizontal axis is the inclination angle and the vertical axis is the emission intensity. Including Examples 1 to 3 (30 degrees, 15 degrees, and 45 degrees) and Comparative examples (0 degrees), the emission intensity was examined in increments of 5 degrees from 0 degrees to 45 degrees. The light amount was measured in a predetermined range with the optical axis as the center.

  As shown in FIG. 8, in this fluorescent glass, it was found that the emission intensity is remarkably improved when the inclination angle is 15 degrees or more, and particularly, the emission intensity is extremely increased when the inclination angle is 30 degrees or more and 35 degrees or less. In addition, since the data is in increments of 5 degrees, the exact critical angle is unknown, but the emission intensity has decreased from 35 degrees beyond 30 degrees, and there is a critical angle between 30 degrees and 35 degrees. Inferred. And in the area | region beyond the critical angle, as shown in FIG. 7, it is guessed that the peak of emitted light intensity separates from on an optical axis.

  Next, as shown in FIG. 9, a metal film 109 is formed by vapor deposition on the side surface 107c of the fluorescent glass 107 in the light emitting devices 101 of Examples 1 to 3, and how much the light intensity changes depending on the presence or absence of the metal film 109. Examined. Here, the material of the metal film 109 was aluminum. FIG. 10 is a graph of LED element currents measured by the light emitting devices of Examples 1 and 4 and the output of light emitted from the light emitting devices. The light output was measured at a wavelength of 1020 nm.

  As shown in FIG. 10, it has been found that when the metal 109 is formed, the emission intensity is reduced as compared with the case where the metal 109 is not formed. This is because the reflection using the surface of the metal film 109 has a larger loss than the total reflection using the refractive index difference. Therefore, in the fluorescent glass in which the inclined surface is formed, total reflection using the difference in refractive index is preferable.

DESCRIPTION OF SYMBOLS 1 Light-emitting device 2 Case 2a Recessed part 2b Reflector part 3 LED element 4 1st lead 5 2nd lead 6 Sealing resin 7 Fluorescent glass 7a Incidence surface 7b Output surface 7c Side surface 7d Optical axis 8 Metal film 9 Void 9a Transparent resin 101 Light-emitting device DESCRIPTION OF SYMBOLS 103 LED element 106 Sealing resin 107 Fluorescent glass 107a Incident surface 107b Outgoing surface 107c Side surface 107d Optical axis 201 Light emitting device 103 LED element 106 Sealing resin 109 Metal film 207 Fluorescent glass 207a Incident surface 207b Outgoing surface 207c Side surface 207d Optical axis

Claims (7)

A light source;
Rare earth ions that form a luminescent center are uniformly contained in the matrix, and the rare earth ions constitute substantially one material with the matrix material, an incident surface on which excitation light emitted from the light source is incident, and wavelength conversion It is to have a, an exit surface for emitting light, the excitation light is to the excitation light glass phosphor wavelength converted light is emitted radially from absorbed by the rare earth ions in the rare earth ions incident on the rare earth ions And comprising
The glass phosphor, at least a portion of the sides, to name an inclined surface inclined with respect to the optical axis so as to spread toward the entrance side to the exit side,
When the inclination angle of the inclined surface is increased from a state parallel to the optical axis, the emission intensity on the optical axis becomes the highest when the inclination angle is equal to or less than a predetermined critical angle, and the inclination angle exceeds the predetermined critical angle. The position with the highest emission intensity moves away from the optical axis,
The light emitting device having an inclination angle of the inclined surface with respect to the optical axis of 15 degrees or more and 35 degrees or less . The light emitting device according to claim 1, wherein an inclination angle of the inclined surface with respect to the optical axis is not less than 30 degrees and not more than 35 degrees. Adjacent to the outside of the inclined surface, a transparent medium transparent to the wavelength-converted light is disposed,
The light incident on the inclined surface with a glass fluorescent body, the light emitting device according to claim 1 or 2, the total reflection due to the difference in the refractive index of the translucent material and the glass phosphor. 4. The light emitting device according to claim 1, wherein an inclination angle of the inclined surface is equal to or less than the predetermined critical angle. 5. The light emitting device according to any one of claims 1 to 3 , wherein an inclination angle of the inclined surface exceeds the predetermined critical angle. The light source is a semiconductor light emitting element,
The light emitting device according to claim 1, wherein the glass phosphor seals the semiconductor light emitting element.   The light emitting device according to any one of claims 1 to 6, wherein emission centers of the glass phosphor are Yb ions and Nd ions.

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