Patent Publication Number: US-2023151946-A1

Title: Wavelength conversion member, method of manufacturing same, and light-emitting device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to Japanese Patent Application No. 2021-186402 filed on Nov. 16, 2021, the disclosure of which is hereby incorporated by reference in its entirety. 
     BACKGROUND 
     The present disclosure relates to a wavelength conversion member, a method of manufacturing the same, and a light-emitting device. 
     Japanese Patent Application Publication No. 2021-507307 A describes a device including a phosphor ceramic on which light from a plurality of light-emitting diodes is incident. The device has an optical barrier in the phosphor ceramic to reduce propagation of light in a lateral direction. The phosphor ceramic is formed, for example, by repeatedly folding, slicing, and firing two or more layer films composed of a phosphor ceramic precursor and a light barrier/reflector/scatterer. 
     SUMMARY 
     An object of the present disclosure is to provide a wavelength conversion member including a wavelength conversion portion including a plurality of light-emitting portions, wherein an effect of reducing propagation of light from an adjacent light-emitting portion is improved, and a method of manufacturing the same. Another object of the present invention is to provide a light-emitting device including the wavelength conversion member. 
     A method of manufacturing a wavelength conversion member according to an embodiment of the present disclosure includes: preparing a composite by layering a layered body and a ceramic sheet that includes a phosphor, the layered body including a pair of light-reflective green sheets each containing a reflective material, and a light-shielding green sheet containing a light shielding material with the light-shielding green sheet being layered between the pair of reflective green sheets; and pressurizing and firing the composite. 
     A wavelength conversion member according to an embodiment of the present disclosure includes: a plurality of light-emitting portions including a ceramic containing a phosphor as a main material; and a plurality of layered bodies each including a pair of light reflecting layers and a light shielding layer arranged between the pair of light reflecting layers. The layered bodies and the light-emitting portions are alternately aligned in a layering direction of the layered bodies. 
     A light-emitting device according to an embodiment of the present disclosure includes: a wavelength conversion member according to an embodiment of the present disclosure; and a plurality of semiconductor laser elements positioned with respect to the wavelength conversion member so that light emitted from each of the plurality of semiconductor laser elements is incident on a respective one of the light-emitting portions, Each of the light-emitting portions is configured to convert the light incident from a corresponding one of the plurality of semiconductor laser elements into light having a different wavelength. 
     According to an embodiment of the present disclosure, it is possible to provide a wavelength conversion member including a wavelength conversion portion including a plurality of light-emitting portions, wherein an effect of suppressing propagation of light from an adjacent light-emitting portion is improved, and a method of manufacturing the same. Also, it is possible to provide a light-emitting device including this wavelength conversion member. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a schematic perspective view of a wavelength conversion member according to a first embodiment. 
         FIG.  2    is a schematic diagram illustrating a method of manufacturing the wavelength conversion member according to the first embodiment. 
         FIG.  3    is another schematic diagram illustrating the method of manufacturing the wavelength conversion member according to the first embodiment. 
         FIG.  4    is even another schematic diagram illustrating the method of manufacturing the wavelength conversion member according to the first embodiment. 
         FIG.  5    is yet another schematic diagram illustrating the method of manufacturing the wavelength conversion member according to the first embodiment. 
         FIG.  6    is still another schematic diagram illustrating the method of manufacturing the wavelength conversion member according to the first embodiment. 
         FIG.  7    is further another schematic diagram illustrating the method of manufacturing the wavelength conversion member according to the first embodiment. 
         FIG.  8    is a still yet another schematic diagram illustrating the method of manufacturing the wavelength conversion member according to the first embodiment. 
         FIG.  9    is a schematic perspective view of a wavelength conversion member according to a first modification example of the first embodiment. 
         FIG.  10    is a schematic perspective view of a wavelength conversion member according to a second modification example of the first embodiment. 
         FIG.  11    is a schematic perspective view of a wavelength conversion member according to a third modification example of the first embodiment. 
         FIG.  12    is a schematic perspective view of a wavelength conversion member according to a second embodiment. 
         FIG.  13    is a schematic top view of a light-emitting device according to a third embodiment. 
         FIG.  14    is a cross-sectional view of the light-emitting device taken along the line XIV-XIV in  FIG.  13   . 
         FIG.  15    is a schematic top view illustrating the light-emitting device according to the third embodiment from which the wavelength conversion member, a light-transmissive member, and a light shielding member are removed. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Hereinafter, certain embodiments of the invention will be described with reference to the drawings. In the following description, terms indicating a specific direction or position (e.g., “upper”, “lower”, and other terms including those terms) are used as necessary. The use of those terms, however, is to facilitate understanding of the invention with reference to the drawings, and the technical scope of the present invention is not limited by the meaning of those terms. In addition, parts having the same reference numerals appearing in a plurality of drawings indicate identical or equivalent parts or members. 
     In the present disclosure, for polygonal shapes such as triangles and quadrangles, shapes in which the corners of the polygon are rounded, chamfered, beveled, coved, and the like, are also referred to as polygonal shapes. Furthermore, not only shapes with such modifications at corners (ends of sides) but also shapes with modifications at intermediate portions of sides are similarly referred to as polygons. In other words, a polygon-based shape with a partial modification is included in the interpretation of the “polygonal shape” described in the present disclosure. 
     The same applies not only to polygons but also to terms representing specific shapes such as trapezoids, circles, protrusions, and recesses. Furthermore, the same applies when dealing with each side forming that shape. In other words, even when on a corner or an intermediate portion of a side is modified, the interpretation of “side” includes the modified portion. When a “polygonal shape” or a “side” without partially modification is to be distinguished from a shape with modification, “in a strict sense” will be added to the description as in, for example, “quadrangle in a strict sense”. 
     Further, the following embodiments exemplify a wavelength conversion member, etc. for embodying the technical idea of the present invention, and the present invention is not limited to the description below. In addition, unless otherwise specified, the dimensions, materials, shapes, relative arrangements, and the like of constituent elements described below are not intended to limit the scope of the present invention to those alone, but are intended to be exemplified. The contents described in one embodiment can be applied to other embodiments and modification examples. The size, positional relationship, and the like of the members illustrated in the drawings can be exaggerated in order to clarify the explanation. Furthermore, in order to avoid excessive complication of the drawings, a schematic view in which some elements are not illustrated may be used, or an end view illustrating only a cutting surface may be used as a cross-sectional view. 
     First Embodiment 
       FIG.  1    is a schematic perspective view of a wavelength conversion member according to a first embodiment. As illustrated in  FIG.  1   , the wavelength conversion member  10  includes a plurality of light-emitting portions  20  and a plurality of layered bodies  30 . Components of the wavelength conversion member  10  will be described. In  FIG.  1   , an X-axis, a Y-axis, and a Z-axis that are mutually orthogonal are illustrated for reference. Directions parallel to the X-axis, the Y-axis, and the Z-axis are defined as a first direction X, a second direction Y, and a third direction Z, respectively. 
     Light-Emitting Portion  20   
     The light-emitting portions  20  each have an upper surface, a lower surface opposite to the upper surface, and a plurality of lateral surfaces meeting the upper surface and the lower surface. In  FIG.  1   , in each of the light-emitting portions  20 , the third direction Z is a direction perpendicular to the upper surface and/or the lower surface thereof. The plurality of lateral surfaces are connected to an outer edge of the upper surface and an outer edge of the lower surface. Each of the light-emitting portions  20  has, for example, a rectangular parallelepiped shape. Further, the upper surface of each of the light-emitting portions  20  is rectangular. In the example of  FIG.  1   , each of the light-emitting portions  20  is a cube. The upper surface, the lower surface, and the four lateral surfaces of each of the light-emitting portions  20  are all square. However, the shape of each of the light-emitting portions  20  is not limited these shapes. 
     In each of the light-emitting portions  20 , the upper surface or the lower surface may be a light incident surface, and the lower surface or the upper surface may be a light emission surface. Light having a predetermined wavelength incident on the light incident surface can be converted into light having a different wavelength, and the converted light can be emitted from the light emission surface. Each of the light-emitting portions  20  may emit a portion of the incident light. Each of the light-emitting portions  20  may convert all the incident light into light having a different wavelength. In this case, the light incident on each of the light-emitting portions  20  is not emitted from each of the light-emitting portions  20 . 
     Each of the light-emitting portions  20  is irradiated with light, and thus each of the light-emitting portions  20  is preferably formed mainly of an inorganic material that is not easily decomposed by light irradiation as a base material. The main material is, for example, a ceramic. Examples of the ceramic used for the main material include, aluminum oxide, aluminum nitride, silicon oxide, yttrium oxide, zirconium oxide, and magnesium oxide, etc. The main material of the ceramic is preferably selected from materials having a melting point in a range of 1200° C. to 2500° C. in order to prevent deterioration caused by heat, such as deformation or discoloration, of each of the light-emitting portions  20 . Each of the light-emitting portions  20  is, for example, a sintered body formed from a ceramic as a main material. 
     Each of the light-emitting portions  20  can be formed by sintering, for example, a phosphor and a light-transmissive material such as aluminum oxide. The content of the phosphor can be in a range of 0.05 vol % to 50 vol % with respect to the total volume of the ceramic. Further, for example, each of the light-emitting portions  20  may be formed by sintering a powder of the phosphor, that is, using a ceramic substantially consisting of only the phosphor. Furthermore, each of the light-emitting portions  20  may be formed from a single crystal of a phosphor. 
     Examples of the phosphor include yttrium aluminum garnet (YAG) activated with cerium, lutetium aluminum garnet (LAG) activated with cerium, silicate activated with europium ((Sr, Ba) 2 SiO 4 ), αSiAlON phosphor, and βSiAlON phosphor. Among them, the YAG phosphor has good heat resistance. Thus, each of the light-emitting portions  20  is mainly made of a ceramic having a phosphor. 
     For example, in a case in which each of the light-emitting portions  20  includes the YAG phosphor, when blue excitation light is incident on the lower surface, white light can be emitted from the upper surface by combining the blue excitation light and yellow fluorescence. 
     Layered Body  30   
     Each of the layered bodies  30  is a structure in which a light reflecting layer  31 , a light shielding layer  32 , and the light reflecting layer  31  are layered in this order. In  FIG.  1   , the light reflecting layer  31  and the light shielding layer  32  are indicated by dot patterns having different densities instead of assigning reference numerals to all of the light reflecting layer  31  and the light shielding layer  32 . 
     The light reflecting layer  31  has light reflectivity. The light reflecting layer  31  has a reflectivity of 70% or more with respect to light incident from the light-emitting portion  20 . The light reflecting layer  31  more preferably has a reflectivity of 80% or more. A thickness of the light reflecting layer  31  is preferably in a range of 30 μm to 1000 μm, for example. 
     As a main material of the light reflecting layer  31 , for example, a ceramic can be used. Examples of the ceramic to be used as the main material include aluminum oxide, yttrium oxide, titanium oxide, zirconium oxide, and silicon oxide. The light reflecting layer  31  may be formed from a material other than the ceramic. 
     The light shielding layer  32  is adapted to shield or attenuate incident light. The light shielding layer  32  preferably has a transmittance of 20% or less with respect to incident light. More preferably, the light shielding layer  32  has a transmittance of 15% or less. With such a light transmittance of the light shielding layer  32 , it is possible to reduce interference of light between the light-emitting portions  20  described below. Also, the light shielding layer  32  can contain a light absorber. 
     In this case, the light shielding layer  32  preferably has an absorptance of 70% or more for light incident through the light reflecting layer  31 . More preferably, the light shielding layer  32  has an absorptance of 80% or more. With such a configuration, the effects described above can be further enhanced. The light shielding layer  32  may not contain a light absorber. 
     A thickness of the light shielding layer  32  is preferably in a range of 30 μm to 1000 μm, for example. 
     The light shielding layer  32  is, for example, a layer containing the same ceramic as the main material forming the light reflecting layer  31  as a main material and further containing a dark-colored ceramic that absorbs light. Examples of the dark color include black, brown, navy blue, and gray. Among them, the black color having a high light absorptance is preferable. When the main material of the light shielding layer  32  is the same ceramic as a ceramic used as the main material of the light reflecting layer  31 , it is possible to reduce the possibility of occurrence of cracking, breaking, etc., due to a difference in shrinkage rate during sintering in the manufacturing step of the wavelength conversion member  10  described later. The main material of the light shielding layer  32  may be a ceramic that is different from the main material of the light reflecting layer  31 . Examples of the ceramic used as the main material of the light shielding layer  32  include aluminum oxide, yttrium oxide, titanium oxide, zirconium oxide, silicon oxide, etc., which are exemplified above as the ceramic used as the main material of the light reflecting layer  31 . Examples of the dark-colored ceramic included in the light shielding layer  32  along with the ceramic of the main material include ruthenium oxide, aluminum nitride, silicon nitride, etc. In this specification, a ceramic having a property of absorbing light is included in the light absorber. The light shielding layer  32  may be formed from a material other than a ceramic. 
     Wavelength Conversion Member  10   
     In  FIG.  1   , the light reflecting layer  31 , the light shielding layer  32 , and the light reflecting layer  31  are layered in the first direction X in each layered body  30  (hereinafter, the first direction X in  FIG.  1    may be referred to as a layering direction). In the wavelength conversion member  10 , the light-emitting portion  20  and the layered body  30  are alternately aligned in the layering direction of the layered body  30 . In other words, in the wavelength conversion member  10 , each layered body  30  is disposed between light-emitting portions  20  adjacent to each other in the layering direction, and the light-emitting portions  20  are separated from each other with a respective layered body  30  disposed therebetween. Each of the light-emitting portions  20  is disposed such that, in a top view, the centers of the light-emitting portions  20  are aligned on a straight line parallel to the layering direction. 
     In the illustrated wavelength conversion member  10 , among the plurality of light-emitting portions  20 , at each of two light-emitting portions  20  that are opposite outermost light-emitting portions  20  in the layering direction (first direction X), the light reflecting layer  31  is provided on a lateral surface of a respective light-emitting portion  20  opposite to a lateral surface of the respective light-emitting portion in contact with the layered body  30 . In the illustrated example, the light reflecting layers  31  are provided on both ends of the wavelength conversion member  10 . The light reflecting layer  31  provided in contact with the light-emitting portion  20  is a lateral surface of the wavelength conversion member  10 . At the light reflecting layer  31  located at each of both ends, the light shielding layer  32  is not provided on a lateral surface of the light reflecting layer  31  opposite to a lateral surface of the light reflecting layer  31  in contact with the light-emitting portion  20 . The wavelength conversion member is not limited to have the configuration in which the light reflecting layers  31  are disposed on both ends, and may be in various forms. This will be described below. 
     The wavelength conversion member  10  has a rod-like shape having a square planar shape when viewed in the layering direction. In the present specification, the term “rod-like shape” refers to a shape elongated in the layering direction. The planar shape of the wavelength conversion member  10  when viewed from the layering direction is not necessarily a square. The lengths in the layering direction of the light-emitting portions  20  are preferably equal to each other. Additionally, the lengths in the layering direction of the layered bodies  30  are preferably equal to each other. Accordingly, the pitch of the light-emitting portions  20  can be made uniform in the wavelength conversion member  10 . In the present specification, the term “equal” allows a difference within ±10%. The pitch of the light-emitting portions  20  can be, for example, in a range of 0.1 mm to 2.0 mm. The variation in the pitch of the light-emitting portions  20  can be, for example, ±5% or less with respect to the average value of the pitch of the light-emitting portions  20 . 
     In the layering direction, the length of each of the layered bodies  30  is preferably shorter than the length of each of the light-emitting portions  20 . With this structure, the pitch of the light-emitting portions  20  can be narrowed in the wavelength conversion member  10 . The length of each of the layered bodies  30  may be the same as or longer than the length of each of the light-emitting portions  20  in the layering direction. In the layering direction, the length of each of the light-emitting portions  20  is, for example, in a range of 0.3 mm to 2.0 mm. More preferably, the length of each of the light-emitting portions  20  is in a range of 0.5 mm to 1.5 mm. In the layering direction, the length of each of the layered bodies  30  is, for example, in a range of 0.1 mm to 2.0 mm. In the layering direction, the length of each of the layered bodies  30  may be equal to or greater than a half of a length of the respective light-emitting portion  20  and equal to or less than twice the length of the respective light-emitting portion  20 . 
     The wavelength conversion member  10  has the plurality of light-emitting portions  20 , and the layered body  30  is disposed between adjacent ones of the light-emitting portions  20 . This allows for reducing interference of the light when light enters the adjacent light-emitting portions  20 . This is described in detail below. 
     In each of the light-emitting portions  20 , the light reflecting layers  31  are disposed in contact with the two lateral surfaces intersecting the layering direction. Accordingly, light that is wavelength-converted by the phosphor included in each of the light-emitting portions  20  and emitted from the lateral surface of each of the light-emitting portions  20  toward the light reflecting layer  31  is reflected to each of the light-emitting portions  20 . Further, light that is incident on a respective light-emitting portion  20 , is not wavelength-converted by the respective light-emitting portion  20 , and is emitted from a lateral surface of the respective light-emitting portion  20  toward the light reflecting layer, is reflected to each of the light-emitting portions  20 . This allows for improving the luminous efficacy of each of the light-emitting portions  20 . 
     Furthermore, from the perspective of further improving the luminous efficiency of each of the light-emitting portions  20 , the light reflecting layer  31  is preferably formed from a ceramic. When light from each of the light-emitting portions  20  reaches the surface of the light reflecting layer  31 , the light including the evanescent light seeps into the light reflecting layer  31 . When the light reflecting layer  31  is formed from a ceramic, absorption of seeped light from each of the light-emitting portions  20  can be reduced and reflection of light can be increased as compared with a case in which the light reflecting layer  31  is formed from metal, etc. Therefore, it is possible to reduce a decrease in the luminous efficiency of each of the light-emitting portions  20 . 
     The light shielding layers  32  are disposed such that light reflecting layers  31  are in contact with two lateral surfaces of each light shielding layer  32  that intersect the layering direction. Each light shielding layer  32  is disposed so as to be located between adjacent light-emitting portions  20  in the layering direction. Accordingly, it is possible to reduce interference of light emitted from adjacent light-emitting portions  20 . The light reflecting layer  31  and the light-emitting portion  20  are arranged in this order on both lateral sides of each light shielding layer  32 . The arrangement of the light-emitting portion  20 , the light reflecting layer  31 , and the light shielding layer  32  will be further described below. 
     In the illustrated example, one of the plurality of light-emitting portions  20  included in the wavelength conversion member  10  is referred to as a first light-emitting portion, and a light-emitting portion adjacent to the first light-emitting portion with the layered body  30  disposed therebetween is referred to as a second light-emitting portion. Light incident on the first light-emitting portion includes a portion of light that is not wavelength-converted by the phosphor and travels in a direction toward the adjacent second light-emitting portion. Most of the portion of the light is reflected at the light reflecting layer  31  and returns to the first light-emitting portion side. A portion of the light incident on the first light-emitting portion and wavelength-converted by the phosphor travels toward an adjacent second light-emitting portion, but a large part of the portion of the light is reflected at the light reflecting layer  31  and returns to the first light-emitting portion side. A portion of the light incident on the light reflecting layer  31  from the first light-emitting portion may pass through the light reflecting layer  31  and seep toward the second light-emitting portion. However, an entirety or a part of the seeped light from the light reflecting layer  31  toward the second light-emitting portion is absorbed by the light shielding layer  32 . Thus, light reaching the second light-emitting portion can be reduced as compared with the case in which the light shielding layer  32  is not provided. Similarly, a large portion of the light incident on the second light-emitting portion and traveling toward the first light-emitting portion after wavelength conversion by the phosphor and/or a large portion of the light traveling toward the first light-emitting portion without wavelength conversion is reflected at the light reflecting layer  31  and returns to the second light-emitting portion side. A portion of the light incident on the light reflecting layer  31  from the second light-emitting portion may pass through the light reflecting layer  31  and seep toward the first light-emitting portion. However, an entirety or a part of the seeped light is absorbed by the light shielding layer  32 . Thus, light reaching the first light-emitting portion can be reduced as compared with the case in which the light shielding layer  32  is not provided. In this manner, it is possible to reduce the interference between the light incident on the first light-emitting portion and the light incident on the second light-emitting portion. 
     Thus, for example, when light is incident on the first light-emitting portion and is not incident on the second light-emitting portion, it is possible to reduce propagation of a portion of the light incident on the first light-emitting portion to the second light-emitting portion and light emission from the second light-emitting portion. 
     That is, it is possible to realize the wavelength conversion member  10  that improves the effect of reducing the propagation of light from an adjacent light-emitting portion  20 . As a result, light can be emitted individually from each of the light-emitting portions  20  without substantially causing interference with light in adjacent light-emitting portions  20 . In addition, the effect of reducing the propagation of light from the adjacent light-emitting portions  20  can be obtained even when a thickness of the layered body  30  is reduced, and thus it is possible to realize the wavelength conversion member  10  in which the propagation of light from an adjacent light-emitting portion  20  is reduced and the pitch of the light-emitting portions  20  is reduced. 
     When the layered body  30  is formed only from the light shielding layer  32 , the light shielding layer  32  absorbs a large portion of the seeped light from the light-emitting portion  20  including evanescent light, and thus the luminous efficiency of the light-emitting portion  20  may be decreased. In the wavelength conversion member  10 , with the layered body  30  having a layered structure of the light reflecting layer  31 , the light shielding layer  32 , and the light reflecting layer  31 , a large portion of the seeped light from the light-emitting portion  20  can be reflected at the light reflecting layer  31 , and a portion of the light passing through the light reflecting layer  31  without being reflected at the light reflecting layer  31  can be absorbed by the light shielding layer  32 . Accordingly, it is possible to improve the luminous efficiency of the light-emitting portion  20  and impede the light emitted by each of the light-emitting portions  20  from being incident on another light-emitting portion  20 . 
     In addition, for example, in a case in which laser light is incident on the light-emitting portion  20 , generation of heat from the light-emitting portion  20  may be larger than in a case in which light from a light-emitting diode is incident on the light-emitting portion  20 . Because a ceramic is less likely to deteriorate even at a high temperature due to heat generated by the light-emitting portion  20 , forming the light reflecting layer  31  from a ceramic allows for maintaining the functions of the layered body  30  and the light-emitting portion  20 . 
     Method of manufacturing Wavelength Conversion Member 
     A method of manufacturing a wavelength conversion member according to the first embodiment includes: preparing a composite in which a layered body and a ceramic sheet having a phosphor are alternately layered, the layered body including a green sheet including a reflective material, a green sheet including a light shielding material, and the green sheet including the reflective material that are layered in this order; and pressurizing and firing the composite. The method of manufacturing the wavelength conversion member according to the first embodiment may include other steps. 
       FIGS.  2  to  6    are schematic diagrams illustrating a method of manufacturing the wavelength conversion member according to the first embodiment. Here, the method of manufacturing the wavelength conversion member  10  illustrated in  FIG.  1    is described as an example of the method of manufacturing the wavelength conversion member according to the first embodiment with reference to  FIGS.  2  to  6    sequentially. In  FIGS.  5  and  6   , the X-axis, the Y-axis, and the Z-axis orthogonal to each other are illustrated for reference. Directions parallel to the X-axis, the Y-axis, and the Z-axis are defined as a first direction X, a second direction Y, and a third direction Z, respectively. 
     First, as illustrated in  FIG.  2   , a required number of a green sheet  31 S (light-reflective green sheet) having a reflective material, a green sheet  32 S (light-shielding green sheet) having a light shielding material, and a ceramic sheet  20 S having a phosphor is prepared. The green sheets  31 S and  32 S are obtained by, for example, preparing a slurry containing powders, binders, solvents, etc., as main materials and performing a known method such as a doctor-blade method. When a plurality of the green sheets  31 S are used, the slurry is preferably adjusted so that the green sheets  31 S have the same density. In this manner, shrinkage rates of the green sheets  31 S before and after firing (a ratio of the dimension of the green sheet  31 S after firing to the dimension of the green sheet  31 S before firing) can be made uniform between the green sheets  31 S, so that the variation in the thicknesses of the light reflecting layer  31  after the firing can be reduced. When a plurality of the green sheets  32 S are used, the slurry is preferably adjusted so that the green sheets  32 S have the same density. In this manner, shrinkage rates of the green sheets  32 S before and after firing (a ratio of the dimension of the green sheet  32 S after firing to the dimension of the green sheet  32 S before firing) can be made uniform between the green sheets  32 S, so that the variation in the thicknesses of the light shielding layer  32  after the firing can be reduced. In the present specification, the phrase “having the same density” means that the difference in density (g/cm 3 ) is within 10%. Examples of the main material of the green sheets  31 S,  32 S include aluminum oxide, yttrium oxide, titanium oxide, zirconium oxide, silicon oxide, etc. The green sheet  32 S further includes a light absorber mixed with the main material. Examples of the light absorber to be mixed include ruthenium oxide, aluminum nitride, silicon nitride, etc. 
     The ceramic sheet  20 S is obtained, for example, by preparing a slurry containing a phosphor powders, binders, solvents, etc., obtaining a phosphor green sheet by using a known method such as a doctor-blade method, and firing the phosphor green sheet at a predetermined temperature. In order to increase the density, the ceramic sheet  20 S is preferably fired at a temperature higher than a firing temperature in a firing step described later. The ceramic sheet  20 S is prepared so as to have a thickness equal to a length of one side of the light-emitting portion  20  of the wavelength conversion member  10  to be obtained. Examples of the phosphor contained in the ceramic sheet  20 S include yttrium aluminum garnet (YAG) activated with cerium, lutetium aluminum garnet (LAG) activated with cerium, silicate activated with europium ((Sr, Ba) 2 SiO 4 ), αSiAlON phosphor, and βSiAlON phosphor. 
     Each sheet preferably has a rectangular shape with substantially the same size, for example, in a top view viewed from above the largest surface of the sheet. When each sheet has a rectangular shape in a top view, the wavelength conversion member  10  can be efficiently prepared in the cutting step to be described below in the case of preparing the rod-shaped wavelength conversion member  10 . In addition, the portion to be discarded after the cutting step can be reduced. The shape of each sheet in a top view is not limited thereto, and may be a parallelogram, a circle, an elliptical shape, or another shape. 
     Subsequently, as illustrated on the upper side of the arrow in  FIG.  3   , a plurality of layered bodies  30 S are prepared such that the green sheet  31 S, the green sheet  32 S, and the green sheet  31 S are layered in this order in each of the layered bodies  30 S. Furthermore, the thickness of the layered body  30 S is adjusted by pressurization, etc., such that the pitch between the light-emitting portions  20  of the wavelength conversion member  10  to be prepared becomes a desired size. In consideration of the subsequent pressurizing step and the firing step, it is desirable that the thickness of the layered body  30 S is preferably 1.2 to 2 times the pitch between the light-emitting portions  20  of the wavelength conversion member  10 . Then, as illustrated on the lower side of the arrow in  FIG.  3   , the plurality of layered bodies  30 S and the plurality of ceramic sheets  20 S are alternately layered to prepare a composite  100  (composite preparation step). In the example of  FIG.  3   , the green sheets  31 S are disposed below the lowermost ceramic sheet  20 S and above the uppermost ceramic sheet  20 S, respectively. 
     The composite  100  may be prepared by layering sheets in order from the lower sheet illustrated in  FIG.  3   . 
     Preparing the plurality of layered bodies  30 S in each of which the three green sheets  31 S and  32 S are layered and then alternately layering the plurality of layered bodies  30 S and the plurality of ceramic sheets  20 S to prepare the composite  100  allows for reducing unevenness in shrinkage of each layered body  30 S in the pressurizing step of the composite  100  to be described below. 
     As compared with the case in which the green sheets  31 S and the green sheet  32 S are adjusted in thickness to respective desired thicknesses and laminated one by one together with the ceramic sheets  20 S, adjusting a thickness of each layered body  30 S in which the three green sheets are laminated and laminating each layered body  30 S with the ceramic sheet  20 S allows for reducing deviations in the thicknesses of the layered bodies  30 S to serve as the pitch between the light-emitting portions  20  of the wavelength conversion member  10 , so that variations in the thicknesses among the laminated bodies  30 S can be reduced. In  FIG.  3   , the green sheet  31 S and the green sheet  32 S are indicated by dot patterns having different densities instead of assigning reference numerals to all of the green sheets  31 S and  32 S. The same applies to  FIGS.  4  to  6    to be described below. 
     Subsequently, the composite  100  illustrated in  FIG.  3    is pressurized and fired to prepare the composite  100 A illustrated in  FIG.  4   . Specifically, first, the composite  100  illustrated in  FIG.  3    is pressurized from the upper and lower surface (pressurizing step). The pressurization of the composite  100  can be performed by, for example, a cold isostatic pressing device, etc. In the pressurizing step, a pressure of 80 MPa or more is preferably applied to the composite  100 . It is more preferable that a pressure of 100 MPa or more is applied in the pressurization. Thus, the density of the green sheets  31 S and  32 S can be increased, so that the shrinkage rate of the green sheets  31 S and  32 S during firing can be reduced, which allows for reducing the occurrence of cracks in the green sheets  31 S and  32 S during firing. Furthermore, the variation in thickness of the green sheets  31 S and  32 S after firing can be reduced. Also, the thickness of the green sheets  31 S and  32 S after firing can be reduced, so that the wavelength conversion member  10  having a narrow pitch of the light-emitting portions  20  can be realized. 
     Subsequently, the composite  100  after the pressurization is fired to obtain the composite  100 A (firing step). In the firing step, the firing temperature is, for example, from 1300 to 1500° C. The firing of the composite  100  can be performed, for example, by a hot press, etc. At this time, the firing is preferably performed while applying pressure to upper and lower surfaces of the composite  100 . A pressure applied to the composite  100  in the firing step is lower than a pressure applied to the composite  100  in the pressurizing step. In the firing step, a pressure of, for example, 10 MPa or less is applied to the composite  100 . The pressurizing step and the firing step may be performed simultaneously. That is, the firing may be performed while applying the composite  100  to a pressure of 100 MPa or more, for example. 
     The shrinkage rate of the ceramic sheet  20 S before and after the steps of pressurizing and firing the composite  100  is smaller than the shrinkage rate of the layered body  30 . In other words, with the ceramic sheet  20 S fired at a temperature higher than the firing temperature in the firing step before the composite preparation step, almost no contraction in the layering direction occurs in the steps of pressurizing and firing the composite  100 . On the other hand, the green sheets  31 S and  32 S shrink in the layering direction by about 20 to 30% in the pressurizing step and about 10% in the firing step. That is, the thickness of the ceramic sheet  20 S in the composite body  100 A is similar to the thickness of the ceramic sheet  20 S in the composite body  100 , but the thicknesses of the green sheets  31 S and  32 S in the composite body  100 A are smaller than the thicknesses of the green sheets  31 S and  32 S in the composite body  100 . Reduction in thickness of the green sheet  31 S and  32 S allows for narrowing the pitch of the ceramic sheets  20 S. The lengths of the plurality of the layered bodies  30 S in the layering direction after firing are preferably equal to each other. Accordingly, the pitch of the light-emitting portions  20  can be made uniform in the wavelength conversion member  10  to be obtained. As used herein, the term “equal” allows a difference within ±10%. 
     Subsequently, as illustrated in  FIGS.  5  and  6   , the composite  100 A is cut to prepare a plurality of the wavelength conversion members  10  (a plurality of composite pieces). In the illustrated example, the layering direction coincides with the first direction X. The composite  100 A can be cut using, for example, a wire saw. 
     As illustrated in  FIG.  5   , the composite  100 A is cut in a plane parallel to a first plane formed by the first direction X and the second direction Y. The cutting surface parallel to the first plane is parallel to the layering direction (first direction X) of the composite  100 A. In the example illustrated in  FIG.  5   , the composite  100 A is cut in the layering direction along a plurality of dot-dash lines CL 1  parallel to the second direction Y, to prepare a plurality of composites  100 B. In the example illustrated in  FIG.  5   , there are fourteen dot-dash lines CL 1 , and fifteen composites  100 B are prepared. Any appropriate number of dot-dash lines CL 1  can be set, and the number of dot-dash lines CL 1  is not limited to the example of  FIG.  5   . The terms “parallel” and “perpendicular” in the present specification allows a deviation within ±5 degrees. The same applies to the description of  FIG.  6   . 
     In the present specification, a surface of the composite or the wavelength conversion member (the composite piece) that is not perpendicular to a straight line parallel to the layering direction (first direction X) is referred to as a “layering surface”. More specifically, the layering surface is a plane parallel to a straight line parallel to the layering direction (first direction X) of the composite. The illustrated composite has four layering surfaces. For example, in each of the composites  100 B illustrated in  FIG.  5   , four lateral surfaces parallel to the layering direction (first direction X) are layering surfaces. Specifically, two lateral surfaces parallel to the XY plane and the two lateral surfaces parallel to the XZ plane, are layering surfaces. In the illustrated example, the two lateral surfaces parallel to the YZ plane are not included in the layering surfaces. That is, a surface having a lateral surface of one sheet or layer, for example, a surface having a lateral surface of the ceramic sheet  20 S or the light reflecting layer  31 , is not referred to as the layering surface. A surface having a lateral surface of two or more sheets or layers is referred to as the layering surface. The layering surface includes a surface that is a portion or the whole of the lateral surface of the composite  100 A before being cut. Further, the layering surface includes a cutting surface formed when performing the cutting described above, and a cutting surface parallel to the first plane, and a cutting surface parallel to a second plane described below is included in the layering surface in which the plurality of ceramic sheets  20 S and the layered body  30 S are layered. 
     The method includes a step of grinding the layering surface of the composite  100 B after preparing the composite  100 B. Specifically, the two layering surfaces parallel to the first plane (layering surfaces parallel to the XY plane) including the cutting surface formed in the cutting step described above are ground. By grinding the two layering surfaces of the composite  100 B, the variation in the thickness of the third direction Z of each ceramic sheet  20 S can be reduced. Also, the thickness of each ceramic sheet  20 S in the third direction Z can be adjusted to the desired thickness. The method may further include a polishing step of polishing the two layering surfaces described above. By polishing the two layering surfaces, the surface accuracy of the two layering surfaces of the composite  100 B can be improved. For example, the polished layering surface can be an upper or lower surface of the wavelength conversion member  10  made to be subsequently singulated and prepared. Note that all four layering surfaces may be ground and polished, or the polishing step may not be provided. 
     Subsequently, as illustrated in  FIG.  6   , the composite  100 B is cut in a plane parallel to a second plane formed from the first direction X and the third direction Z. The cutting surface formed by cutting a plane parallel to the second plane is in a direction parallel to the first direction X (layering direction) of the composite  100 B. The first plane and the second plane are planes parallel to the first direction X (layering direction). That is, the cutting surface formed during cutting in the cutting step is parallel to the layering direction. In a plane perpendicular to the layering direction, the composites  100 A,  100 B are not cut. In the example illustrated in  FIG.  6   , the composite  100 B is cut in the vertical direction along a plurality of dot-dash lines CL 2  parallel to the first direction X, to prepare the plurality of wavelength conversion members  10 . In the example illustrated in  FIG.  6   , three of the dot-dash lines CL are provided, and four wavelength conversion members  10  are prepared from one composite  100 B. Since fifteen composites  100 B are prepared in the step of  FIG.  5   , a total of sixty wavelength conversion members  10  are prepared in this step. The number of dot-dash lines CL 2  is discretionary, and is not limited to the example of  FIG.  6   . In the prepared wavelength conversion member  10 , the layer formed by firing the green sheet  31 S having the reflective material and the layer formed by firing the green sheet  32 S having the light shielding material are made of a ceramic, and the light shielding material includes a light absorber. 
     The first plane and the second plane intersect each other. The first plane and the second plane are preferably orthogonal to each other. With this configuration, the cutting surface formed when cutting is performed in a plane parallel to the first plane and the cutting surface formed when cutting is performed in a plane parallel to the second plane are orthogonal to each other. Cutting along planes orthogonal to each other allows for efficiently preparing the rod-shaped wavelength conversion member  10 , for example, when the composite  100  is prepared by layering rectangular sheets. At this time, the upper surface, the lower surface, and the lateral surface of the wavelength conversion member  10  are rectangular. The angle at which the two cutting surfaces intersect each other is not limited to a right angle. By performing cutting in two planes, the wavelength conversion member  10  having a desired shape can be manufactured regardless of the shape of the composite  100 . In a case in which the plurality of wavelength conversion members  10  having a desired shape can be manufactured only by cutting in one plane, the cutting in the two planes is unnecessary. 
     Examples of such a case include a case in which one side of the wavelength conversion member is extremely short and a case in which only a small number of wavelength conversion members are prepared. 
     The composite preparation step is not limited to the step of alternately layering the plurality of layered bodies  30 S and the plurality of ceramic sheets  20 S, as illustrated in  FIG.  3   . The composite preparation step may be, for example, a step of preparing a composite  100 C by layering one layered body  30 S and one ceramic sheet  20 S, as illustrated in  FIG.  7   . Additionally, as illustrated in  FIG.  8   , the composite preparation step may be a step of layering the ceramic sheets  20 S on both sides of one layered body  30 S to prepare a composite  100 D. In a case in which the composite illustrated in  FIGS.  7  and  8    is prepared, the method of manufacturing the wavelength conversion member according to the present invention is effective. 
     In the present specification, the “step of alternately layering the ceramic sheet  20 S and the layered body  30 S” includes the step of preparing the composite illustrated in  FIGS.  7  and  8   . Also, the “step of alternately layering the plurality of ceramic sheets  20 S and the layered body  30 S” does not include the step of preparing the composite illustrated in  FIG.  7   , and includes the step of preparing the composite illustrated in  FIG.  8   . The “step of alternately layering the plurality of ceramic sheets  20 S and the plurality of layered bodies  30 S” does not include the step of preparing the composite illustrated in  FIGS.  7  and  8   . 
     In this manner, in the method of manufacturing the wavelength conversion member  10  according to the first embodiment, it is possible to realize the method of manufacturing the wavelength conversion member  10  that improves the effect of suppressing the propagation of light from the adjacent light-emitting portions  20 . Further, in the method of manufacturing the wavelength conversion member  10  according to the first embodiment, the pitch of the light-emitting portions  20  is determined by the thicknesses of the light reflecting layer  31  prepared by firing the green sheet  31 S and the light shielding layer  32  prepared by firing the green sheet  32 S. In addition, by adjusting the densities of the green sheets  31 S and  32 S, errors caused by shrinkage of the green sheets  31 S and  32 S in the firing step can be reduced. Therefore, by setting the green sheets  31 S and  32 S to predetermined thicknesses, the pitch of the light-emitting portions  20  can be made substantially constant in the formed wavelength conversion member  10 . That is, it is possible to prepare the wavelength conversion member  10  in which the plurality of light-emitting portions  20  are disposed with high positional accuracy. 
     Modification Example of Wavelength Conversion Member 
       FIG.  9    is a schematic perspective view of a wavelength conversion member according to a first modification example of the first embodiment. In the wavelength conversion member  10  illustrated in  FIG.  1   , the light reflecting layers  31  are disposed at both ends in the layering direction (first direction X), but the light reflecting layers  31  may not be disposed at both ends in the layering direction as in a wavelength conversion member  10 A illustrated in  FIG.  9   . In the wavelength conversion member  10 A, both ends in the layering direction are the light-emitting portions  20 . In other words, the two lateral surfaces perpendicular to the layering direction (first direction X) of the wavelength conversion member  10 A are the lateral surfaces of the light-emitting portions  20 . Even if the light reflecting layers  31  are not disposed at both ends in the layering direction as in the wavelength conversion member  10 A, when different light beams are incident on the adjacent light-emitting portions  20 , an effect of suppressing interference between the light beams can be obtained. 
     The wavelength conversion member  10 A can be prepared by preparing the composite without disposing the green sheets  31 S on a lower side of the ceramic sheet  20 S disposed on a lowermost side and an upper side of the ceramic sheet  20 S disposed on an uppermost side among the plurality of ceramic sheets  20 S in the step illustrated in  FIG.  3   , and then performing the same steps as those illustrated in  FIGS.  4  to  6   . 
       FIG.  10    is a schematic perspective view of a wavelength conversion member according to a second modification example of the first embodiment. In a wavelength conversion member  10 B illustrated in  FIG.  10   , the light reflecting layer  31  and the light shielding layer  32  may be sequentially disposed at each of both ends in the layering direction from the side closer to the light-emitting portion  20 . In a plan view viewed from the layering direction, the lateral surface of the light shielding layer  32  is a lateral surface of the wavelength conversion member  10 B. The light reflecting layer  31  is disposed so as to be in contact with a lateral surface opposite to a lateral surface of the light shielding layer  32  serving as a lateral surface of the wavelength conversion member  10 B.  FIG.  11    is a schematic perspective view of a wavelength conversion member according to a third modification example of the first embodiment. As in a wavelength conversion member  10 C illustrated in  FIG.  11   , both ends in the layering direction may be the layered bodies  30 . In a plan view viewed from the layering direction, the lateral surface of the light reflecting layer  31  is a lateral surface of the wavelength conversion member  10 C. Furthermore, the light shielding layer  32 , the light reflecting layer  31 , and the light-emitting portion  20  are disposed in this order so as to be in contact with the lateral surface of the light reflecting layer  31  serving as a lateral surface of the wavelength conversion member  10 C. The light reflecting layer  31 , the layered body of the light reflecting layer  31  and the light shielding layer  32 , or the layered body  30  is preferably disposed at each of both ends in the layering direction as in the wavelength conversion members  10 ,  10 B, and  10 C because the amount of seeped light from the light-emitting portions  20  in the layering direction can be made uniform or close to uniform between the two light-emitting portions  20  closest to both ends in the layering direction and the other light-emitting portions  20 . This can reduce color unevenness and luminance unevenness between the light-emitting portions  20 . 
     The wavelength conversion member  10 B can be prepared by disposing the green sheets  32 S on the lower side of the lowermost green sheet  31 S and the upper side of the uppermost green sheet  31 S to prepare the composite in the step illustrated in  FIG.  3   , and then performing the same steps as those illustrated in  FIGS.  4  to  6   . The wavelength conversion member  10 C can be prepared by preparing the composite without disposing the layered bodies  30  instead of the green sheets  31 S on a lower side of the ceramic sheet  20 S disposed on a lowermost side and an upper side of the ceramic sheet  20 S disposed on an uppermost side among the plurality of ceramic sheets  20 S in the step illustrated in  FIG.  3   , and then performing the same steps as those illustrated in  FIGS.  4  to  6   . 
     Second Embodiment 
       FIG.  12    is a schematic perspective view of a wavelength conversion member according to a second embodiment. In  FIG.  12   , the X-axis, the Y-axis, and the Z-axis that are mutually orthogonal are illustrated for reference. Directions parallel to the X-axis, the Y-axis, and the Z-axis are defined as a first direction X, a second direction Y, and a third direction Z, respectively. The wavelength conversion member according to the present embodiment further includes a light reflecting portion  40  in the wavelength conversion member  10  according to the first embodiment, such as a wavelength conversion member  10 D illustrated in  FIG.  12   . In the following description, to distinguish the wavelength conversion member  10 D and the wavelength conversion member  10 , the wavelength conversion member  10  is referred to as a layered portion  15 . Note that the wavelength conversion member  10 D may include any of the wavelength conversion members  10 A,  10 B,  10 C instead of the wavelength conversion member  10  as the layered portion  15 . 
     The light reflecting portion  40  is, for example, a frame-shaped member having a rectangular opening. The light reflecting portion  40  includes an upper surface, a lower surface opposite to the upper surface, one or more inner lateral surfaces connecting an inner edge of the upper surface and an inner edge of the lower surface, and one or more outer lateral surfaces connecting an outer edge of the upper surface and an outer edge of the lower surface. The outer edge and the inner edge of the upper surface, and the outer edge and the inner edge of the lower surface have, for example, rectangular shapes. In this case, the light reflecting portion  40  includes four inner lateral surfaces having the rectangular shapes and four outer lateral surfaces having the rectangular shapes. Note that the outer edge and the inner edge of the upper surface and the outer edge and the inner edge of the lower surface are not limited to the rectangular shape, and they can have any shape such as a circle, an oval, and a polygon. 
     The light reflecting portion  40  is, for example, a sintered body formed of a ceramic as a main material. The ceramic used for the main material includes, for example, aluminum oxide, aluminum nitride, silicon oxide, yttrium oxide, zirconium oxide, magnesium oxide, etc. Among them, aluminum oxide is preferable from the perspective of high reflectivity. Among these ceramics, aluminum oxide is also a preferable main material because of its relatively high thermal conductivity. Note that the light reflecting portion  40  may not contain a ceramic as the main material. 
     In the wavelength conversion member  10 D, in a top view, the light reflecting portion  40  surrounds two layering surfaces and two lateral surfaces perpendicular to the layering direction of the layered portion  15 . That is, the inner lateral surfaces of the light reflecting portion  40  are connected to two layering surfaces of the four layering surfaces of the layered portion  15 . The other two layering surfaces do not connect to the inner lateral surfaces of the light reflecting portion  40 . Specifically, the light reflecting portion  40  is connected to two lateral surfaces of each of the light-emitting portions  20 , two lateral surfaces of each of the layered bodies  30 , and two lateral surfaces in the layering direction of the wavelength conversion member  10 , that is, surfaces perpendicular to the layering direction of the two light reflecting layers  31  located at both ends. The wavelength conversion member  10 D has a flat plate shape and is, for example, a rectangular parallelepiped. 
     The two layering surfaces of the layered portion  15  that do not connect to the inner lateral surfaces of the light reflecting portion  40  may be part of the upper surface and the lower surface of the wavelength conversion member  10 D. At this time, the upper surface of the layered portion  15  and the upper surface of the light reflecting portion  40  form, for example, one continuous plane. The lower surface of the layered portion  15  and the lower surface of the light reflecting portion  40  form, for example, one continuous plane. The upper surface and/or the lower surface of the layered portion  15  may have a shape protruding from the upper surface and/or the lower surface of the light reflecting portion  40 , respectively. In this case, four lateral surfaces of the layered portion  15  are at least partially exposed outward of the inner lateral surfaces of the light reflecting portion  40 . 
     The wavelength conversion member  10 D can be manufactured in a slip casting manner, for example. Specifically, the method of manufacturing the wavelength conversion member  10 D includes a step of disposing a member containing a ceramic material around the composite  100 B (in this case, the layered portion  15  having the same structure as that of the wavelength conversion member  10 ) that is cut in the step illustrated in  FIG.  6    to form the light reflecting portion  40  connected to the two layering surfaces of the cut composite  100 B. In addition, the step of disposing the member containing the ceramic material to form the light reflecting portion  40  includes a step of disposing the member in a liquid state containing the ceramic material around the two layering surfaces of the cut composite  100 B and firing the member. In this specification, the term “ceramic” refers to a ceramic after firing, and the term “ceramic material” refers to a ceramic material before firing. 
     By disposing a member in a liquid state containing a ceramic material around the layered portion  15  and firing the member, a large number of voids can be contained in the vicinity of the boundary with the layered portion  15  to increase a void ratio of the formed light reflecting portion  40 , allowing for decreasing the void ratio in the vicinity of the outer edge distant from the layered portion  15  as compared with the vicinity of the boundary. By increasing the void ratio in the vicinity of the boundary of the light reflecting portion  40 , it is possible to increase the light reflectance in the vicinity of the boundary with the layered portion  15 . Furthermore, by reducing the void ratio in the vicinity of the outer edge of the light reflecting portion  40 , the density in the vicinity of the outer edge can be increased, and the strength of the entire wavelength conversion member  10 D can be ensured. 
     It is preferable that the density of the light reflecting portion  40  in the vicinity of the boundary with the layered portion  15  is lower than the density of the light reflecting layer  31  formed by firing the green sheet  31 S having the reflective material. As described above, by increasing the void ratio of the light reflecting portion  40  in the vicinity of the boundary with the layered portion  15 , a larger reflection region due to air is formed at the boundary between the lateral surface of each of the light-emitting portions  20  and the inner lateral surface of the light reflecting portion  40 , and the effect of reflecting light incident on the inner lateral surface of the light reflecting portion  40  from the light-emitting portion  20  side to the light-emitting portion  20  side can be enhanced. With such a structure, the light extraction efficiency of the wavelength conversion member  10 D can be increased. The void ratio can be adjusted by a sintering condition (sintering temperature, sintering time, rate of temperature increase), a type and particle size of materials, concentration of a sintering aid, etc. 
     For example, in the wavelength conversion member  10 D illustrated in  FIG.  12   , when a vertical cross section cut in the layering direction (first direction X) so as to pass through a straight line connecting respective midpoints of two sides extending in the second direction Y of the upper surface of the layered portion  15  is observed with a scanning electron microscope (SEM), it can be determined that the light reflecting portion  40  has a lower density than the light reflecting layer  31  in a case in which the proportion (for example, area ratio) of voids included in the light reflecting portion  40  is higher than the proportion of voids included in the light reflecting layer  31 . 
     Third Embodiment 
     In a third embodiment, an example of a light-emitting device employing the wavelength conversion member according to the second embodiment will be described.  FIG.  13    is a schematic top view of a light-emitting device according to a third embodiment.  FIG.  14    is a cross-sectional view of the light-emitting device taken along the line XIV-XIV in  FIG.  13   .  FIG.  15    is a schematic top view illustrating the light-emitting device according to the third embodiment from which the wavelength conversion member, a light-transmissive member, and a light shielding member are removed. In  FIGS.  13  to  15   , the X-axis, the Y-axis, and the Z-axis orthogonal to each other are shown for reference. Directions parallel to the X-axis, the Y-axis, and the Z-axis are defined as a first direction X, a second direction Y, and a third direction Z, respectively. 
     The light-emitting device according to the third embodiment includes a plurality of light-emitting elements, and a wavelength conversion member, wherein the light emitted from each of the plurality of light-emitting elements is incident on a different light-emitting portion of the wavelength conversion member, and each light-emitting portion converts incident light into light having a different wavelength. 
     An illustrated light-emitting device  200  is an example of the light-emitting device according to the third embodiment. The light-emitting device  200  includes the wavelength conversion member  10 D, a package  210 , a plurality of light-emitting elements  220 , one or more submounts  230 , one or more light reflective members  240 , a light-transmissive member  280 , and a light shielding member  290 . 
     Each of the components of the light-emitting device  200  will be described. Description of the wavelength conversion member  10 D is omitted. 
     Package  210   
     The package  210  includes a base portion  211  and a frame portion  212  surrounding the base portion  211  and extending upward. The frame portion  212  has a stepped portion  213  on the inner side thereof. The base portion  211  has an upper surface  211   a  and a lower surface. The frame portion  212  includes an upper surface  212   a , one or more inner lateral surfaces  212   c , and one or more outer lateral surfaces  212   d . The stepped portion  213  is provided inside the frame portion  212  and has an inner lateral surface  212   c  connected to an upper surface  213   a  of the frame portion. The upper surface  213   a  of the stepped portion  213  is located above the upper surface  211   a  of the base portion and below the upper surface  212   a  of the frame portion. A plurality of electrodes are provided on the upper surface  212   a  of the illustrated frame portion  212 . 
     The package  210  can be formed, for example, of a ceramic as a main material. For example, aluminum nitride, silicon nitride, aluminum oxide, or silicon carbide can be used as the ceramic. The package  210  is not limited to ceramic, and may mainly be another material such as metal. 
     Light-Emitting Element  220   
     The light-emitting element  220  is, for example, a semiconductor laser element. The light-emitting element  220  is not limited to a semiconductor laser element, and may be, for example, a light-emitting diode (LED) or an organic light-emitting diode (OLED). 
     The light-emitting element  220  has, for example, a rectangular outer shape in a top view. A lateral surface intersecting one of the two short sides of the rectangle serves as an emission surface of light emitted from the light-emitting element  220 . Further, an upper surface and a lower surface of the light-emitting element  220  each have a larger area than the emission surface. 
     A case in which the light-emitting element  220  is a semiconductor laser element will be described below. The light (laser beam) emitted from the light-emitting element  220  exhibits divergence and an elliptical far field pattern (hereinafter referred to as “FFP”) on a plane parallel to the emission surface. 
     As used herein, the FFP indicates a shape and a light intensity distribution of the emitted light at a position apart from the emission surface. 
     In the elliptical shape of light emitted from the light-emitting element  220 , a long-diameter direction of the elliptical shape is referred to as a fast axis direction of the FFP, and a short-diameter direction of the elliptical shape is referred to as a slow axis direction of the FFP. The fast axis direction of the FFP in the light-emitting element  220  may coincide with a layering direction in which a plurality of semiconductor layers including an active layer of the light-emitting element  220  are layered. 
     Based on the light intensity distribution of the FFP of the light-emitting element  220 , light having an intensity of 1/e 2  times or greater of a peak intensity value is referred to as a main part of light. In this light intensity distribution, an angle corresponding to the intensity of 1/e 2  is referred to as a divergence angle. The divergence angle of the FFP in the fast axis direction is greater than the divergence angle of the FFP in the slow axis direction. 
     Further, light at the center of the elliptical shape of the FFP, in other words, light exhibiting a peak intensity in the light intensity distribution of the FFP, is referred to as light traveling on an optical axis or light passing through an optical axis. Further, the optical path of the light traveling on the optical axis is referred to as the optical axis of the light. 
     As the light-emitting element  220 , for example, a semiconductor laser element that emits blue light can be employed. 
     Blue light refers to light having an emission peak wavelength within a range of 420 nm to 494 nm. When a semiconductor laser element is used in combination with a YAG phosphor, for example, a semiconductor laser element that emits light having a peak wavelength of 480 nm or less is preferably used in consideration of the excitation efficiency. 
     Examples of the semiconductor laser element that emits blue light include a semiconductor laser element including a nitride semiconductor. GaN, InGaN, and AlGaN, for example, can be used as the nitride semiconductor. As the light-emitting element  220 , a semiconductor laser element that emits light other than blue light may be used. 
     Submount  230   
     The submount  230  is configured, for example, in a rectangular parallelepiped shape and has a lower surface, an upper surface, and a lateral surface. Note that the shape of the submount  230  need not necessarily be the rectangular parallelepiped. The submount  230  is formed using, for example, aluminum nitride or silicon carbide, although other materials may be used. Further, a metal film, for example, is provided on the upper surface of the submount  230 . 
     Light Reflective Member  240   
     The light reflective member  240  has a light reflecting surface that reflects light. The light reflecting surface is, for example, a surface having a light reflectance of 90% or more to the peak wavelength of the irradiated light. The light reflectance in the example herein may be 100% or may be less than 100%. The light reflecting surface is inclined with respect to a lower surface of the light reflective member  240 . The inclination angle of the light reflecting surface relative to the lower surface is, for example, 45 degrees. 
     For the light reflective member  240 , it is preferable to select a heat-resistant material as a main material, and for example, glass such as quartz or BK7 (borosilicate glass), metal such as aluminum, or Si can be used. The light reflecting surface can be formed using, for example, metal such as Ag or Al, or a dielectric multilayer film of Ta 2 O 5 /SiO 2 , TiO 2 /SiO 2 , or Nb 2 O 5 /SiO 2 . As used herein, the expression “A/B” indicates a multilayer film in which a film A and a film B are layered in order. 
     Light-Transmissive Member  280   
     The light-transmissive member  280  is a member having transmissivity. As used herein, the phrase “having transmissivity” means that the light transmittance with respect to the peak wavelength of incident light is 80% or more. The light-transmissive member  280  includes an upper surface, a lower surface opposite to the upper surface, and lateral surfaces intersecting the upper surface and the lower surface. The lateral surfaces connect an outer edge of the upper surface and an outer edge of the lower surface. The light-transmissive member  280  is, for example, a rectangular parallelepiped or a cube. In this case, both the upper surface and the lower surface of the light-transmissive member  280  are rectangular, and the light-transmissive member  280  has four rectangular lateral surfaces. 
     However, the light-transmissive member  280  is not limited to being the rectangular parallelepiped or the cube. That is, in the top view, the shape of the light-transmissive member  280  is not limited to the rectangular shape, and it can have any shape such as a circle, an oval, and a polygon. 
     The light-transmissive member  280  has a base material formed in a flat plate shape such as a rectangular parallelepiped. The base material of the light-transmissive member  280  can be formed using, for example, sapphire as a main material. Sapphire is a material with relatively high transmittance and relatively high strength. In addition to sapphire, a light-transmissive material including quartz, silicon carbide, glass, etc. may be used as the main material. 
     Light Shielding Member  290   
     The light shielding member  290  can be formed of, for example, a resin having light shielding properties. Here, “light shielding properties” indicate properties that do not allow light to pass through, and the light shielding properties may be implemented by utilizing light absorbing properties, light reflective properties, etc. in addition to the light blocking properties. The light shielding member  290  can be formed, for example, by containing fillers made of a light diffusing material and/or a light absorbing material in the resin. 
     Examples of the resin that forms the light shielding member  290  include an epoxy resin, a silicone resin, an acrylate resin, a urethane resin, a phenol resin, and a BT resin. Examples of the light absorbing fillers contained in the light shielding member  290  include dark-colored pigments such as carbon black. 
     Light-Emitting Device  200   
     In the example of the light-emitting device  200  illustrated, the wavelength conversion member  10 D is joined to the upper surface of the light-transmissive member  280 . The wavelength conversion member  10 D is smaller than the light-transmissive member  280  in a top view, for example. The light-transmissive member  280  is joined to the lower surface of the wavelength conversion member  10 D on the upper surface thereof. In a top view, each of the light-emitting portions  20  of the wavelength conversion member  10 D is located inside the outer edge shape of the upper surface of the light-transmissive member  280 . 
     The outer peripheral portion of the lower surface of the light-transmissive member  280  is joined to, for example, the upper surface  213   a  of the stepped portion  213  provided inside the frame portion  212  of the package  210 . The light-transmissive member  280  is joined to the package  210  to form a closed space in which the light-emitting element  220  is disposed. In this manner, in the light-emitting device  200 , the light-transmissive member  280  can serve as a lid member. This closed space is formed in a hermetically sealed state. By being hermetically sealed, collection of dust such as organic substances on the emission surface of the light-emitting element  220  can be suppressed. 
     In the illustrated example of the light-emitting device  200 , five light reflective members  240  are disposed on the upper surface  211   a  of the base portion  211 . The five light reflective members  240  are disposed on the same metal film, for example, and the lower surface of the metal film is joined to the upper surface  211   a  of the base portion  211 . The five light reflective members  240  may each be disposed on a different metal film. The five light reflective members  240  are disposed at predetermined intervals in the X direction in a top view, for example. 
     In the illustrated example of the light-emitting device  200 , one submount  230  is disposed on the upper surface  211   a  of the base portion  211 . The submount  230  is disposed on the metal film, and the lower surface of the metal film is joined to the upper surface  211   a  of the base portion  211 . The submount  230  has a rectangular shape in a top view, for example, and is disposed in the X direction on the long side of the rectangle. The submount  230  is disposed on the metal film on which the light reflective member  240  is disposed. Note that the submount  230  and the light reflective member  240  may be disposed on different metal films. A plurality of the submounts  230  may be disposed on the metal film. 
     Each of the light-emitting elements  220  is disposed on the upper surface  211   a  of the base portion  211 . Specifically, each of the light-emitting elements  220  is disposed on the upper surface of the submount  230 . In the illustrated example of the light-emitting device  200 , five light-emitting elements  220  are disposed on the upper surface of the same submount  230 , and the lower surface of the submount  230  is joined to the upper surface  211   a  of the base portion  211 . Additionally, the five light-emitting elements  220  have a rectangular shape in a top view, for example, and are disposed at predetermined intervals in the X direction with the long side of the rectangle facing the Y direction. In a top view, the emission surface of each of the light-emitting elements  220  is parallel or perpendicular to the inner lateral surface  212   c  or the outer lateral surface  212   d  of the frame portion  212 . Each of the light-emitting elements  220  is disposed such that their emission surfaces face in the same direction. Each of the light-emitting elements  220  may be disposed on the upper surfaces of different submounts  230 . 
     Each light reflective member  240  includes a light reflecting surface inclined toward each of the light-emitting elements  220 . In each of the light-emitting elements  220 , the light emitted from the emission surface is applied to the light reflecting surface of the corresponding light reflective member  240 . The corresponding light reflective member  240  is a light reflective member  240  having a surface facing the emission surface of each light-emitting element  220  in a top view. The light-emitting element  220  is disposed such that at least the main part of light is irradiated to the light reflecting surface. 
     The main part of the light emitted by each light-emitting element  220  is reflected by the light reflecting surface of the corresponding light reflective member  240  and enters the light-transmissive member  280 . The main part of the light reflected by the light reflecting surface of each light reflective member  240  is incident on each of the light-emitting portions  20  after passing through the light-transmissive member  280 . Part or all of the light incident on each of the light-emitting portions  20  is converted into light having a different wavelength by each of the light-emitting portions  20 . The light incident on each of the light-emitting portions  20  or the light wavelength-converted by each of the light-emitting portions  20  is emitted from the upper surface of each of the light-emitting portions  20  to the outside of the light-emitting device  200 . In the light-emitting device  200 , each light-emitting element  220  can be driven individually. 
     The light shielding member  290  is formed above the light-transmissive member  280 . The light shielding member  290  is formed so as to fill a gap between the frame portion  212  of the package  210  and the wavelength conversion member  10 . The light shielding member  290  can be formed by, for example, pouring a thermosetting resin and curing the poured resin with heat. By providing the light shielding member  290 , leakage of light is suppressed. 
     The light shielding member  290  does not reach the upper surface of the wavelength conversion member  10 D. Alternatively, even when the light shielding member  290  reaches the upper surface of the light reflecting portion  40  of the wavelength conversion member  10 D, the light shielding member  290  does not reach the upper surface of the light-emitting portion  20 . 
     In the light-emitting device  200 , the plurality of light-emitting portions  20  are disposed in the wavelength conversion member  10 D with high positional accuracy, so that the main part of the light reflected by the light reflecting surface of each light reflective member  240  can be reliably made incident on the corresponding light-emitting portion  20 . In addition, in the light-emitting device  200 , propagation of light from the adjacent light-emitting portions  20  can be suppressed by the layered body  30 , so that light can be individually incident on each of the light-emitting portions  20  without substantially causing interference of light in the adjacent light-emitting portions  20 , and light subjected to wavelength conversion in the light-emitting portion  20  can be emitted. 
     The light-emitting device  200  can be used, for example, for an on-vehicle headlight. The light-emitting device  200  is not limited thereto, and can be used for illumination, a projector, a head-mounted display, and a light source such as a backlight of other displays. 
     Although the preferred embodiments and the like have been described in detail above, the disclosure is not limited to the above-described embodiments and the like, various modifications and substitutions can be made to the above-described embodiments and the like without departing from the scope described in the claims.