JP2019045844A - Fluorescent member, optical component, and light-emitting device - Google Patents

Abstract

To provide a fluorescent member that offers high luminance and a certain strength.SOLUTION: A fluorescent member 10 comprises a plurality of phosphor particles 11 and an inorganic binder 12, and has an upper surface designated as a light extraction surface. The fluorescent member 10 contains a plurality of voids 13 and, in a cross-section that is parallel to the upper surface of the fluorescent member 10 and cuts through both the phosphor particles 11 and the voids 13, the plurality of voids 13 are more densely distributed near at least one phosphor particle 11 of the plurality of phosphor particles 11.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a fluorescent member, an optical component including the fluorescent member, and a light emitting device including the fluorescent member.

  The wavelength conversion member described in Patent Document 1 is made of a fired product of a phosphor and a ceramic binder.

WO2017-064951

  Conventional wavelength conversion members have room for both brightness and strength at a high level.

  The fluorescent member according to one embodiment of the present invention includes a plurality of phosphor particles and an inorganic binder, and has an upper surface serving as a light extraction surface. Further, the fluorescent member includes a plurality of voids, is parallel to the upper surface, and in a cross section that crosses both the phosphor particles and the voids, the plurality of voids are included in the plurality of phosphor particles. In the vicinity of at least one phosphor particle.

  According to the above, it is possible to obtain a fluorescent member with high luminance and a constant strength.

FIG. 1 is a schematic view of a light emitting device according to the first embodiment. FIG. 2 is a top view of the optical component. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4 is a cross-sectional view in the dotted frame of FIG. FIG. 5 is an enlarged view of a part of a cross-sectional view taken along line VV in FIG. FIG. 6 is an SEM image of the fluorescent member according to the example. FIG. 7 is an SEM image of the fluorescent member according to the comparative example. FIG. 8 is data obtained by measuring the illuminance of the fluorescent member according to the example. FIG. 9 is data obtained by measuring the illuminance of the fluorescent member according to the comparative example. FIG. 10 is a top view of the optical component according to the second embodiment. 11 is a cross-sectional view taken along line XI-XI in FIG. FIG. 12 is a cross-sectional view of a modification of the optical component according to the second embodiment.

  A mode for carrying out the present invention will be described below with reference to the drawings. However, the form shown below is for embodying the technical idea of the present invention, and does not limit the present invention. Note that the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation. Moreover, since the same name and code | symbol have shown the member same or the same quality, the overlapping description is abbreviate | omitted suitably.

<Embodiment 1>
FIG. 1 shows a schematic diagram of a light emitting device 1000 according to the present embodiment. 2 shows a top view of the optical component 100, and FIG. 3 shows a cross-sectional view taken along line III-III in FIG. 4 shows an enlarged view in the dotted frame in FIG. 3, and FIG. 5 shows an enlarged view of a part of the sectional view taken along the line VV in FIG.

  As shown in FIG. 1, the light-emitting device 1000 includes an optical component 100 including a fluorescent member 10, a light source 200 that emits excitation light that irradiates the fluorescent member 10, and directs excitation light from the light source 200 toward the fluorescent member 10. The mirror 300 which reflects, and the lens 400 which images the light from the fluorescent member 10 so that it may become a parallel light beam are provided.

  As shown in FIGS. 2 to 5, the fluorescent member 10 includes a plurality of phosphor particles 11 and an inorganic binder 12 and has an upper surface serving as a light extraction surface. In addition, as shown in FIG. 5, the fluorescent member 10 includes a plurality of voids 13, which is parallel to the top surface of the fluorescent member and crosses both the phosphor particles 11 and the voids 13. Are unevenly distributed in the vicinity of at least one of the plurality of phosphor particles 11.

  According to the fluorescent member 10 described above, the strength of the fluorescent member can be ensured while reducing the spread of light from the phosphor particles 11 in the lateral direction (left and right direction in FIG. 3). Hereinafter, this point will be described.

  A fluorescent member including phosphor particles and an inorganic binder is known. Since the light from the phosphor particles propagates and spreads in the lateral direction in the inorganic binder, the luminance when observed from above usually decreases to some extent. Therefore, it is conceivable to suppress the propagation of light from the phosphor particles by providing a plurality of voids inside the fluorescent member to increase the number of regions having different refractive indexes to facilitate scattering. However, in the fluorescent member, if the number of voids is increased in order to increase the luminance, the strength of the fluorescent member is reduced, and if the number of voids is decreased in order to ensure the strength, it is difficult to reduce propagation from the phosphor particles.

  Therefore, in the present embodiment, a plurality of voids 13 are unevenly distributed in a region close to the phosphor particles 11. Thereby, while ensuring the intensity | strength of the fluorescent member 10 in the area | region far from the fluorescent substance particle 11 and with few space | gaps, propagation of the light from the fluorescent substance particle 11 is prevented in the area | region close | similar to the fluorescent substance particle 11 and there are many space | gaps. it can. Therefore, it is possible to obtain the fluorescent member 10 that maintains a certain strength while increasing the luminance.

  Hereinafter, components of the light emitting device 1000 will be described.

(Optical component 100)
As shown in FIGS. 2 and 3, the optical component 100 includes a base 50 and a fluorescent member 10 bonded to the upper surface of the base 50. A reflective film 20 is provided on the lower surface of the fluorescent member 10. A diffusion prevention layer 30 is provided on the lower surface of the reflection film 20, and the lower surface of the diffusion prevention layer 30 and the upper surface of the base portion 50 are joined by the joining member 40.

(Fluorescent member 10)
As shown in FIG. 3, the fluorescent member 10 has an upper surface serving as a light extraction surface, a lower surface located on the opposite side of the upper surface, and a side surface connecting the upper surface and the lower surface. The fluorescent member 10 includes a plurality of phosphor particles 11, an inorganic binder 12, and a plurality of voids 13. Then, as shown in FIG. 5, the plurality of voids 13 in one section (hereinafter referred to as “cross section X”) that is parallel to the upper surface of the fluorescent member 10 and that crosses both the phosphor particles 11 and the voids 13. Are unevenly distributed in the vicinity of the phosphor particles 11. Thereby, since the brightness | luminance can be made high by suppressing propagation of light in the fluorescent member 10, it can be set as the fluorescent member 10 with a high contrast ratio compared with the case where there is no space | gap. The contrast ratio can be recognized as, for example, a ratio between the maximum luminance and the luminance at a position 1 mm away from the emission intensity distribution on the upper surface of the fluorescent member 10. The above-mentioned “uneven distribution” refers to, for example, observing a photograph taken with a scanning electron microscope (SEM) on a scale at which 10 phosphor particles 11 can be clearly confirmed, and at least one phosphor particle 11 It means that the density of the voids 13 in a region sandwiched between the surface of the particle 11 and a line having a separation distance of 0.1 μm is higher than the density of the voids 13 in the region outside it. Further, “parallel to the upper surface of the fluorescent member 10” includes not only those that are completely parallel to the upper surface of the fluorescent member 10 but also those that are inclined ± 10 degrees. In addition, when the upper surface of the fluorescent member 10 is rough when viewed microscopically, the cross section X is a cross section parallel to the flat upper surface of the fluorescent member 10 when viewed macroscopically.

  The plurality of gaps 13 may be provided in the depth direction from the upper surface of the fluorescent member 10. That is, as shown in FIG. 4, a plurality of voids are formed even in one section (hereinafter referred to as “longitudinal section Y”) that is perpendicular to the upper surface of the fluorescent member 10 and that crosses both the phosphor particles 11 and the voids 13. 13 may be provided. Further, since propagation of light entering from the upper surface of the fluorescent member 10 can also be suppressed, for example, a plurality of voids 13 are unevenly distributed in the vicinity of the phosphor particles 11 in a plurality of cross sections X separated by 10 μm or more. preferable.

  Since the shape of the fluorescent member 10 is easy to produce the fluorescent member 10, it can be a rectangular parallelepiped or a cube that is long in one direction, and is preferably a rectangular parallelepiped. In the case of a rectangular parallelepiped, when viewed from above, the length of the fluorescent member 10 in the left-right direction (the width of the fluorescent member 10 and corresponds to the horizontal length of FIG. 2) is in the range of 10 mm to 15 mm. It is preferable that the length of the fluorescent member 10 in the vertical direction (the depth of the fluorescent member 10 corresponds to the length in the vertical direction in FIG. 2) is preferably in the range of 2 mm to 5 mm. By setting the length equal to or longer than the aforementioned lower limit, the region irradiated with the excitation light can be changed. By setting the length equal to or shorter than the aforementioned upper limit, the area of the fluorescent member 10 becomes excessively large. Can be suppressed.

  The thickness of the fluorescent member 10 (vertical length in FIG. 3) is preferably in the range of 50 μm to 200 μm, and more preferably in the range of 70 μm to 130 μm. By making the thickness equal to or greater than the aforementioned lower limit, it becomes easier to adjust the chromaticity of the mixed light of excitation light and fluorescence, and by making the thickness less than the aforementioned upper limit, the phosphor particles on the upper surface side that tend to generate heat Since the distance from 11 to the base 50 can be shortened, the heat generated in the fluorescent member 10 is easily dissipated to the base 50.

  As shown in FIG. 1, in the fluorescent member 10, the excitation light incident surface for exciting the phosphor particles 11 and the light extraction surface for extracting the fluorescence from the phosphor particles 11 are the same surface, and with respect to the surface. Thus, the optical component 100 in which excitation light is incident from an oblique direction is preferable. In such an optical component 100, since the excitation light is difficult to be extracted from above (directly above), the fluorescence color is strong in the light extracted from above the fluorescent member 10, and the excitation light color tends to be weak. For example, when the excitation light is blue and the fluorescence is yellow, strong yellow light is easily extracted. On the other hand, according to the fluorescent member 10, since the excitation light can be scattered by the gap 13, the color of the excitation light can be increased in the finally obtained mixed color light.

(Phosphor particles 11)
Examples of the phosphor particles 11 include a YAG (Yttrium Aluminum Garnet) phosphor, a nitrogen-containing calcium aluminosilicate (CaO—Al ₂ O ₃ —SiO ₂ ) phosphor activated by europium and / or chromium, and activated by europium. Silicate ((Sr, Ba) ₂ SiO ₄ ) phosphor, α sialon phosphor, and β sialon phosphor can be used. Among them, it is particularly preferable to use a YAG phosphor. This is because the YAG phosphor is a material having a relatively high heat resistance, so that deterioration due to excitation light can be reduced. Here, the YAG phosphor includes, for example, those in which at least a part of Y is substituted with Tb and those in which at least a part of Y is substituted with Lu. In addition, the YAG phosphor may contain Gd or Ga in the composition.

  The particle diameter of the phosphor particles 11 is preferably in the range of 1 μm to 20 μm, for example, and more preferably in the range of 3 μm to 6 μm. By setting the particle size to be equal to or larger than the above lower limit value, it becomes easy to provide the gap 13, and by setting the particle size to be equal to or smaller than the above upper limit value, it becomes difficult to uniformly arrange the phosphor particles 11 on the fluorescent member 10. As a measuring method of the particle size, for example, it can be measured by obtaining the shortest and longest average of the phosphor particles 11 having a shape close to a circle by using an SEM image of a scale in which 10 phosphor particles are captured.

  The phosphor particles 11 in the fluorescent member 10 are preferably in the range of 40% by mass to 70% by mass, and more preferably in the range of 45% by mass to 60% by mass. By setting it as the mass% more than the above-mentioned lower limit, the space | gap 13 can be formed easily and propagation of the fluorescent substance particle 11 can be made easy to be suppressed. Moreover, since the mass% of the inorganic binder 12 can be ensured by setting the mass% to the above upper limit value or less, it is easy to suppress a decrease in the strength of the fluorescent member 10 and the heat generated by the phosphor particles 11. It becomes easy to diverge. In particular, in the optical component 100 in which the incident surface of excitation light that excites the phosphor particles 11 and the light extraction surface that extracts fluorescence from the phosphor particles 11 are the same surface, if the mass% of the phosphor particles 11 is low, The light incident on the fluorescent member 10 may be absorbed by the metal used for the reflective film 20 without hitting the phosphor particles 11, but is absorbed by the metal by ensuring a certain mass of the phosphor particles 11. Excitation light can be reduced.

(Inorganic binder 12)
The inorganic binder 12 binds the phosphor particles 11. The inorganic binder 12 is preferably made of a material having a thermal expansion coefficient close to that of the fluorescent member 10. As the inorganic binder 12, aluminum oxide, yttrium oxide, or the like can be used.

(Void 13)
The plurality of voids 13 are provided unevenly in the vicinity of the phosphor particles 11. The gap 13 is constituted by a vacuum, the atmosphere, or the like.

  As shown in FIG. 5, in the cross section X, it is preferable that some of the plurality of voids 13 are provided along the phosphor particles 11. Thereby, propagation of light from the phosphor particles 11 can be easily suppressed. In the cross section X, the plurality of voids 13 are preferably provided over 1/2 or more of the entire circumference of the phosphor particles 11, and more preferably provided over 1/3 or more.

  The refractive index of the gap 13 is preferably lower than the refractive index of the inorganic binder 12, and the refractive index of the inorganic binder 12 is preferably lower than the refractive index of the phosphor particles 11. Thereby, since it becomes easy to totally reflect excitation light by each of the interface of the space | gap 13 and the inorganic binder 12, and the interface of the inorganic binder 12 and the fluorescent substance particle 11, it can make it easy to take out excitation light. At this time, it is more preferable that some of the plurality of voids 13 are in direct contact with the phosphor particles 11. Since the refractive index difference between the gap 13 and the phosphor particles 11 is larger than the refractive index difference between the inorganic binder 12 and the phosphor particles 11, it is possible to easily suppress the propagation of light from the phosphor particles 11.

In the cross section X, the area of one void 13 is preferably smaller than the area of one phosphor particle 11. This is because the plurality of voids 13 having a small area can easily reflect the light from the phosphor particles 11 while maintaining the strength of the fluorescent member 10. The area means, for example, that all the voids 13 are smaller than all the phosphor particles 11 by observing a photograph taken with a SEM at a scale where ten phosphor particles 11 are captured. The area of the gap 13 is, for example, 0.01 μm ² or more and 2 μm ² or less.

(Reflective film 20)
A reflective film 20 is provided on the lower surface of the fluorescent member 10. Thereby, the light which goes to the lower surface from the fluorescent member 10 can be reflected upward.

  The reflective film 20 can include at least one of a metal film and a dielectric film. The metal film and the dielectric film may be a single layer or a stacked layer. As the metal film, for example, Al or Ag can be used. As the dielectric film, for example, silicon oxide, titanium oxide, aluminum oxide, or niobium oxide can be used. When both the metal film and the dielectric film are used, the dielectric film and the metal film can be provided in this order from the lower surface side of the fluorescent member 10.

(Diffusion prevention layer 30)
When the reflective film 20 includes a metal film, it is preferable that the diffusion prevention layer 30 is provided on the lower surface of the reflective film 20. Thereby, it is possible to reduce the diffusion of the bonding member 40 into the metal film. As the diffusion prevention layer 30, for example, a material including at least one of Ti, Pt, Au, Pd, and Ta is used. it can.

(Joining member 40)
The joining member 40 fixes the fluorescent member 10 and the base 50. As the bonding member 40, for example, a member mainly containing AuSn, Ag, Al, Au, or the like, or a resin containing a scattering material can be used. In particular, it is preferable to use a eutectic alloy such as AuSn because of high bonding strength.

(Base 50)
The base 50 is made of a material having a higher thermal conductivity than the fluorescent member 10, and the lower surface of the fluorescent member 10 and the upper surface of the base 50 are connected. Thereby, the heat from the fluorescent member 10 is easily dissipated to the base 50, so that deterioration of the phosphor particles 11 can be reduced. When the reflective film 20 and the base 50 are directly joined, the fluorescent member 10 and the base 50 are joined without the joining member 40 interposed therebetween.

  The base 50 includes at least one of a metal and a diffuse reflective ceramic. For example, Cu, CuMo, or CuW can be used as the metal, and aluminum oxide or aluminum nitride can be used as the light diffusing ceramic.

  The thickness of the base portion 50 is preferably in the range of 1 mm or more and 3 mm or less, for example. When the thickness is 1 mm or more, the optical component can be easily handled, and when the thickness is 3 mm or less, the optical component can be prevented from becoming too large.

(Protective film 60)
A protective film 60 may be provided on the upper surface of the fluorescent member 10. As the protective film 60, for example, silicon oxide or niobium oxide is used.

(Method for manufacturing optical component 100)
The fluorescent member 10 included in the optical component can be manufactured by the following method, for example.

  The manufacturing method of the fluorescent member 10 includes the step of mixing the phosphor particles 11 and the ceramic particles, and sintering and integrating the ceramic particles so that the plurality of voids 13 are unevenly distributed in the vicinity of the phosphor particles 11. And obtaining the fluorescent member 10 having the phosphor particles 11, the inorganic binder 12, and the gaps 13. Here, it further includes a step of heat-treating the fluorescent member 10, a step of slicing the fluorescent member 10, and a step of polishing and grinding the upper surface of the fluorescent member 10. In addition, in this specification, in order to simplify description, the fluorescent member before slicing or singulation and the fluorescent member after singulation are collectively referred to as “fluorescent member 10”. Below, each process included in the manufacturing method of the fluorescent member 10 is demonstrated.

  First, phosphor particles 11 and ceramic particles to be inorganic binder 12 later are mixed. At this time, ceramic particles having a sintering temperature lower than the sintering temperature of the phosphor particles 11 are used as the ceramic particles. Thereby, ceramic particles can be sintered while reducing deterioration of the phosphor particles 11 due to heat. The particle diameter of the ceramic particles is preferably smaller than the particle diameter of the phosphor particles 11. Thereby, the adhesive force with the phosphor particles 11 tends to be high. The particle size of the ceramic particles is, for example, preferably in the range of 1/15 or more and 1/2 or less of the phosphor particles 11, and more preferably in the range of 1/12 or more and 1/5. For example, it is preferably in the range of 0.1 μm to 2 μm, and more preferably in the range of 0.3 μm to 1 μm. By setting the particle size to be equal to or larger than the above-mentioned lower limit value, it can be stably produced.

  Next, the ceramic particles are sintered and integrated with the phosphor particles 11 to obtain the phosphor member 10 including the phosphor particles 11 and the inorganic binder 12. As a method for sintering, for example, a spark plasma sintering (SPS) method or a hot press (HP) method can be used. At this time, sintering is performed by adjusting the sintering temperature and time so that the sintered density of the fluorescent member 10 does not become too high.

  When the ceramic particles are sintered, the ceramic particles shrink while being bonded to other nearby ceramic particles. At this time, in the region far from the phosphor particles 11, the ceramic particles are evenly distributed over the entire periphery, so that the ceramic particles are easily bonded to each other. However, in the region near the phosphor particles 11, the phosphor particles 11 are present. This makes it difficult for the ceramic particles to bond together. Thereby, it is considered that the voids 13 are likely to be unevenly distributed in the vicinity of the phosphor particles 11.

  The sintering temperature and time here are the temperature and time at which the surface of the ceramic particles is sintered and the phosphor particles 11 are not sintered. For example, when a YAG phosphor is used as the phosphor particle 11 and aluminum oxide is used as the ceramic particle and sintering is performed using the SPS method, the holding time at the temperature is in the range of 1200 degrees to 1500 degrees. Is preferably performed for a time in the range of 1 minute to 20 minutes.

  The sintered density of the fluorescent member 10 is preferably in the range of 90% to 98%, and more preferably in the range of 93.5% to 96%. By making it not less than the above lower limit value, it is easy to ensure the strength, and by making it not more than the above upper limit value, it is possible to reduce the decrease in luminance and to increase the luminous flux as compared with those having a relatively high sintering density. . The reason why the luminous flux can be increased is considered to be that light is difficult to enter to the side close to the lower surface of the fluorescent member 10 due to the presence of the air gap 13, and thus light absorption by the metal of the reflective film can be reduced. As an example of a method for measuring the sintered density, a method using Archimedes' law is shown below. First, the weight A of the fluorescent member 10 is obtained with a scale. Next, the fluorescent member 10 is put in the water contained in the container so as not to touch the bottom of the container, and the weight B excluding the container and water in water is obtained. Then, the weight A is divided by the weight B (C), the true specific gravity (D) of the phosphor particles 11 and the ceramic particles contained in the fluorescent member 10 is obtained, and C is divided by D to obtain the fluorescent member. A sintered density of 10 can be determined.

  In general, since a sintering mold used in the SPS method or HP method contains carbon, it easily carburizes into an oxide during sintering to cause a reduction reaction, and light is absorbed by carbon. Therefore, in the present embodiment, the fluorescent member 10 obtained by the SPS method or the like is finally heat-treated in an oxidizing atmosphere. Thereby, the oxygen contained in the oxide can be removed to return the deficient oxygen.

  The heat treatment step is preferably performed at a temperature in the range of 1200 ° C. to 1450 ° C. for a time in the range of 1 hour to 40 hours. Oxygen can be easily returned to the oxide contained in the inorganic binder 12 by setting it to the above lower limit value or more, and deterioration of the phosphor particles can be prevented by setting it to the upper limit value or less.

  The obtained fluorescent member 10 may be used as it is, but when the fluorescent member 10 is thicker than the desired fluorescent member 10, the fluorescent member 10 is sliced to be slightly thicker than a predetermined thickness using a wire or the like. To do. You may slice several times so that the fluorescent member 10 of this thickness may be obtained two or more. Furthermore, you may process until it becomes predetermined thickness by grinding | polishing and grinding.

  Next, the reflective film 20 and the diffusion prevention layer 30 are formed on the lower surface of the fluorescent member 10 by sputtering or the like. Next, the fluorescent member 10 is cut into individual pieces by cutting with a blade or the like so as to have a desired shape.

  Next, the bonding member 40 is disposed between the lower surface of the fluorescent member 10 and the upper surface of the base portion 50 to fix the fluorescent member 10 and the base portion 50 together. At this time, it is preferable to perform thermocompression bonding using an AuSn foil as the bonding member 40. Thereby, since it becomes difficult to form a void in the joining member 40 compared with the case where AuSn solder is used, the heat generated in the fluorescent member 10 can be easily dissipated.

  Next, the upper surface of the fluorescent member 10 is washed in order to remove dust attached when the fluorescent member 10 is separated. Before washing, it is preferable to measure the chromaticity of light from the fluorescent member 10 by irradiating the upper surface of the fluorescent member 10 with excitation light. For example, when the phosphor particle 11 is a YAG-based phosphor and the chromaticity obtained by measurement is shifted to a yellow side from the desired chromaticity, acid cleaning with phosphoric acid or the like is performed. Thereby, since the phosphor particles 11 on the surface of the fluorescent member 10 are easily scraped, the chromaticity of the fluorescent member 10 can be made closer to the color of the excitation light to match the desired chromaticity. When the chromaticity obtained by the measurement is within a predetermined chromaticity range, the upper surface of the fluorescent member 10 is cleaned by ultrasonic cleaning.

(Light source 200)
Examples of the light source 200 include a light emitting diode element and a semiconductor laser element. In particular, it is preferable to include a semiconductor laser element. This is because the semiconductor laser element is light with a high directivity, so that the effect of increasing the brightness of the fluorescent member 10 becomes remarkable. Since the semiconductor laser element has a higher output than the light emitting diode element and the fluorescent member 10 easily generates heat, the semiconductor laser element is suitable for use in a reflective optical component 100 as shown in FIG. The light source 200 may include a plurality of semiconductor laser elements. In addition, the light emitting device 1000 may include a plurality of light sources 200.

  The semiconductor laser element or light emitting diode element is preferably one that emits excitation light in the visible region. For example, a nitride semiconductor that has an emission peak wavelength in the range of 430 nm to 480 nm is used. Here, as shown in FIG. 1, the excitation light from the semiconductor laser element is disposed so as to enter the light extraction surface of the fluorescent member 10 at an angle. When the light is incident obliquely, the excitation light is likely to escape in the regular reflection direction, so that the light extracted from above the fluorescent member 10 is likely to be light with a strong fluorescent color. According to the optical component 100, since the excitation light can be reflected and extracted by the gap 13, the color of the excitation light extracted from above the fluorescent member 10 can be increased.

(Mirror 300)
The mirror 300 reflects the excitation light toward the fluorescent member 10. As the mirror 300, for example, MEMS (Micro Electro-Mechanical Systems) can be used. Thereby, excitation light can be irradiated to the fluorescent member 10 while scanning light.

(Lens 400)
Light from the fluorescent member 10 is emitted to the outside through the lens 400. As the lens 400, quartz glass can be used. If the light from the fluorescent member 10 spreads too much, the light incident on the lens 400 is reduced. However, since the luminance can be increased according to the fluorescent member 10, the light from the fluorescent member 10 can easily enter the lens 400.

<Embodiment 2>
As shown in FIGS. 10 and 11, the second embodiment is different from the first embodiment in that the reflective film 20 is not provided on the lower surface of the fluorescent member 10 and the reflective film 20 is provided on the upper surface of the base 50. Is different. Moreover, the lower surface of the fluorescent member 10 has at least one recess, and the fluorescent member 10 and the base 50 are connected by the transparent bonding member 40a. The rest is the same as in the first embodiment.

  When the reflective film 20 is directly formed on the lower surface of the fluorescent member 10 as in the first embodiment, the metal contained in the reflective film 20 may cause migration toward the fluorescent member 10. In this case, a part of the metal enters the inside of the fluorescent member 10 and the amount of light extracted from the fluorescent member 10 decreases. This is considered to be because the metal that has entered the fluorescent member 10 discolors the phosphor particles 11 and / or the inorganic binder 12. Another possible reason is that the metal itself that has entered the fluorescent member 10 absorbs light. Therefore, as shown in FIG. 11, in the optical component 100 according to Embodiment 2, the reflective film 20 is provided on the upper surface of the base 50 instead of the lower surface of the fluorescent member 10, and the fluorescent member 10 and the base 50 are connected to the transparent bonding member. 40a is connected. Thereby, since the transparent joining member 40a is arrange | positioned at the lower surface of the fluorescent member 10, it suppresses that the metal contained in the reflecting film 20 arrange | positioned under the transparent joining member 40a migrates toward the fluorescent member 10. FIG. be able to. As a result, a reduction in the amount of light extracted from the fluorescent member 10 can be suppressed.

  In Embodiment 2, the lower surface of the fluorescent member 10 further has at least one recess. Since the fluorescent member 10 has a plurality of gaps 13, when the lower surface of the fluorescent member 10 is processed to have a predetermined thickness using one or more of slicing, polishing, and grinding, a partial region of one gap 13 is formed. It may be arranged near the lower surface of the fluorescent member 10. In this case, at least one recess is formed on the lower surface of the fluorescent member 10 having the plurality of gaps 13.

  In the case where the lower surface of the fluorescent member 10 has a concave portion, when the reflective film 20 is formed directly on the lower surface of the fluorescent member 10, it is included in the reflective film 20 as compared with the case where the lower surface of the fluorescent member 10 does not have a concave portion. Metal is more prone to migration. As a result, part of the metal enters the inside of the fluorescent member 10 and the amount of light extracted from above the fluorescent member 10 decreases. Therefore, in the second embodiment, the reflective film 20 is provided on the upper surface of the base 50 instead of the lower surface of the fluorescent member 10, and at least one concave portion on the lower surface of the fluorescent member 10 is filled with the transparent bonding member 40a. The fluorescent member 10 and the base 50 are connected by a transparent bonding member 40a. Thereby, it can suppress that the metal contained in the reflecting film 20 arrange | positioned under the transparent joining member 40a migrates toward the fluorescent member 10. FIG. As a result, a decrease in the amount of light extracted from above the fluorescent member 10 can be suppressed.

  As the transparent bonding member 40a, transparent resin (silicone resin, epoxy resin), glass, ceramic, or the like can be used. Among these, it is preferable to use a silicone resin. Thereby, it can be made easy to fill a recessed part with the transparent joining member 40a. Silicone resins are preferred because of their relatively high heat resistance and light transmittance. In this embodiment, the concave portion is filled using the transparent bonding member 40a. However, the bonding member may be provided separately by filling the concave portion with the transparent member.

  As the reflective film 20 provided on the upper surface of the base 50, the same material as the reflective film 20 that can be provided on the lower surface of the fluorescent member 10 in the first embodiment can be used. When the base 50 has reflectivity, the fluorescent member 10 and the base 50 may be connected by the transparent bonding member 40 a without providing the reflective film 20 on the upper surface of the base 50. Here, having the reflectivity means that the base 50 reflects 80% or more of the light wavelength-converted by the fluorescent member 10. Examples of the reflective film 20 having such reflectivity include Ag, Al, and Au.

  The width or diameter of at least one recess on the lower surface of the fluorescent member 10 is the same as the particle diameter of the phosphor particles 11.

  When the transparent bonding member 40 a is disposed on the lower surface of the fluorescent member 10, a part of the transparent bonding member 40 a may climb up the side surface of the fluorescent member 10 and wrap around the upper surface of the fluorescent member 10. In this case, the luminous efficiency of the fluorescent member 10 is reduced. Moreover, the reliability of the fluorescent member 10 will also fall. Therefore, as shown in FIG. 12, a part of the upper surface of the base portion is a convex portion, and the reflective film 20, the transparent bonding member 40a, and the fluorescent member 10 are sequentially arranged on the upper surface of the convex portion of the base portion from below. Can do. Thereby, since the transparent joining member 40a is more likely to travel to the side surface of the convex portion of the base 50 than the side surface of the fluorescent member 10 due to the influence of gravity, the transparent joining member 40a is prevented from wrapping around the upper surface of the fluorescent member 10. be able to.

<Example>
An optical component was manufactured by the following manufacturing method. First, phosphor particles 11 made of a YAG phosphor having a particle size of 5 μm and ceramic particles made of Al ₂ O ₃ having a particle size of 0.5 μm were prepared and mixed by 50 mass%. Next, the mixture was heated at 1310 ° C. for 10 minutes by the SPS method to sinter the ceramic particles. The sintered density of the obtained fluorescent member 10 was 93.7%. Next, the obtained fluorescent member 10 was sliced with a commercially available wire saw. Then, polishing and grinding were performed from the upper surface side of the fluorescent member 10 until the thickness became 100 μm.

  Next, the reflective film 20 made of Al (1 μm), the first layer 31 is Ti (0.2 μm), the second layer 32 is Pt (0.2 μm), and the third layer 33 is formed on the lower surface of the fluorescent member 10. A diffusion preventing layer 30 of Au (0.5 μm) was formed by sputtering from the side closer to the lower surface of the fluorescent member 10. Next, as viewed from the upper surface side, the fluorescent member was separated into individual pieces with a blade so that the length in the longitudinal direction was 12 mm and the length in the lateral direction was 3 mm.

  Next, a base 50 was prepared, the main component of which was made of Cu, and the surface was provided with 2 μm Ni and 100 nm Au plating. The base 50 has a length in the longitudinal direction of 30 mm, a length in the lateral direction of 12 mm, and a thickness of 1.5 mm as viewed from above. First, the base 50 is heated to 250 degrees, and an AuSn foil (Au 22%, Sn 78%) is disposed between the upper surface of the base 50 and the lower surface of the fluorescent member 10. And it heated to 280 degree | times, applying a load, melt | dissolving AuSn foil. Then, after reaching 280 degrees, it was cooled to 250 degrees to complete the joining. Thus, the base 50 and the fluorescent member 10 were joined by thermocompression bonding.

  Next, the chromaticity of light extracted upward from the fluorescent member 10 was measured by irradiating the fluorescent member 10 with laser light having an emission peak wavelength of 450 nm. And the desired chromaticity was obtained by etching the surface of the fluorescent member 10 with the phosphoric acid solution heated at 130 degree | times.

<Comparative example>
The comparative example is substantially the same as the example except that it was sintered at 1450 ° C. for 15 minutes. The sintered density of the obtained fluorescent member was 99.5%.

  FIG. 6 shows an image obtained by observing the cross section X of the fluorescent member 10 according to the example with an SEM, and FIG. 7 shows an image obtained by observing the cross section of the fluorescent member 10 according to the comparative example with an SEM. As can be seen from FIGS. 6 and 7, in the fluorescent member 10 according to the example, the plurality of voids 13 are unevenly distributed in the vicinity of the phosphor particles 11, whereas the fluorescent member according to the comparative example has voids. Confirmed that it does not exist. In the fluorescent member 10 according to the example, the fluorescent member 10 was not damaged when the fluorescent member 10 was thermocompression bonded to the base 50 in the same manner as the fluorescent member according to the comparative example having a high sintered density. It was confirmed that the strength of the member 10 was secured.

  Moreover, the data which measured the illumination intensity of the fluorescent member 10 which concerns on an Example are shown in FIG. 8, and the data which measured the illumination intensity of the fluorescent member which concerns on a comparative example are shown in FIG. Here, laser light having an emission peak wavelength of 445 nm is irradiated from the oblique direction with respect to the upper surface of the fluorescent member so as to be along the longitudinal direction of the fluorescent member as viewed from above (irradiated from the upper left side in FIG. 3). The illuminance on a line crossing the brightest light emitting point in the lateral direction was measured. Specifically, the light extracted from above the fluorescent member was measured with a ProMetric luminance meter manufactured by Radiant Vision Systems. As shown in FIGS. 8 and 9, the fluorescent member according to the comparative example emits light above a certain level even outside the range of ± 1 m from the peak of illuminance, whereas the fluorescent member 10 according to the example from the peak of illuminance. Light is emitted within a range of ± 1 m. From this, in the fluorescent member 10 which concerns on an Example, it has confirmed that the propagation in the fluorescent member 10 could be suppressed. Moreover, when compared within the range of ± 1 m from the peak of illuminance, the illuminance of the fluorescent member 10 according to the example is higher than that of the fluorescent member according to the comparative example. From this, it was confirmed that the fluorescent member 10 according to the example had higher brightness than the fluorescent member according to the comparative example.

  The fluorescent member described in the embodiments can be used for projectors, lighting, vehicular lamps, and the like.

DESCRIPTION OF SYMBOLS 10 ... Fluorescent member 11 ... Phosphor particle 12 ... Inorganic binder 13 ... Gap 20 ... Reflective film 30 ... Diffusion prevention layer 31 ... First layer 32 ... Second layer 33 ... Third layer 40 ... Joining member 40a ... Transparent joining member 50 ... Base 60 ... Protective film 100 ... Optical component 200 ... Light source 300 ... Mirror 400 ... Lens 1000 ... Light emitting device

Claims (16)

A fluorescent member comprising a plurality of phosphor particles and an inorganic binder, and having an upper surface serving as a light extraction surface,
The fluorescent member includes a plurality of voids;
In a cross section that is parallel to the upper surface and that crosses both the phosphor particles and the voids, the plurality of voids are unevenly distributed in the vicinity of at least one phosphor particle of the plurality of phosphor particles. The fluorescent member characterized by the above-mentioned.   2. The fluorescent member according to claim 1, wherein a part of the plurality of voids is provided along the phosphor particles in the one cross section.   3. The fluorescent member according to claim 1, wherein an area of the gap is smaller than an area of the phosphor particles in the one cross section. The refractive index of the void is lower than the refractive index of the inorganic binder,
The refractive index of the inorganic binder is lower than the refractive index of the phosphor particles,
The fluorescent member according to claim 1, wherein some of the plurality of voids are in direct contact with the phosphor particles. The phosphor particles in the fluorescent member are in the range of 40% by mass to 70% by mass,
5. The fluorescence according to claim 1, wherein in the fluorescent member, an incident surface of excitation light for exciting the phosphor particles and an upper surface serving as the light extraction surface are the same surface. Element.   6. The fluorescent member according to claim 1, wherein a particle diameter of the phosphor particles is in a range of 1 μm to 20 μm.   The fluorescent member according to any one of claims 1 to 6, wherein a sintered density of the fluorescent member is in a range of 90% to 98%. Area of the gap, the fluorescent member according to claim 1, characterized in that in the range of 0.01 [mu] m ² or more 2 [mu] m ² or less.   The fluorescent member according to claim 1, wherein the plurality of voids are provided over 1/3 or more of the entire circumference of the phosphor particles. The fluorescent member according to any one of claims 1 to 9, wherein the fluorescent member has a lower surface located on the side opposite to the upper surface,
An optical component comprising: a base connected to a lower surface of the fluorescent member and having a higher thermal conductivity than the fluorescent member.   The optical component according to claim 10, wherein the base includes at least one of a metal and a diffuse reflective ceramic. The base has a reflective upper surface;
The optical component according to claim 10 or 11, wherein the lower surface of the fluorescent member and the upper surface of the base are connected by a transparent bonding member.   The optical component according to claim 12, wherein a reflective film is formed on an upper surface of the base portion. The lower surface of the fluorescent member has at least one recess,
The said at least 1 recessed part is filled with the said transparent joining member, The lower surface of the said fluorescent member and the upper surface of the said base are connected with the said transparent joining member, The Claim 12 or 13 characterized by the above-mentioned. Optical component. The fluorescent member according to any one of claims 1 to 9, or the optical component according to any one of claims 10 to 14,
A semiconductor laser element that irradiates the fluorescent member with excitation light in a visible region,
The semiconductor laser element is a light emitting device in which the excitation light is arranged so as to be incident on the upper surface of the fluorescent member from an oblique direction.   The light emitting device according to claim 15, further comprising a mirror that reflects the excitation light from the semiconductor laser element toward an upper surface of the fluorescent member.

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